Topics of physiological and pathophysiological functions of lymphatics

We have reviewed physiological significance of rhythmical spontaneous contractions of collecting lymphatics, which play an important role in lymph transport and seem to regulate lymph formation through changing the pacemaker sites of the rhythmic contractions and conractile patterns of lymphangions. Next, we reported experimental findings that the wall effective permeability of hydrophilic substances labelled with fluorescent dyes was evaluated in an isolated cannulated rat single lymphatic using a microscope system. With the experimental evidence, we have discussed physiological significance and crucial roles of the enrichment of albumin in lymph through the wall of small lymphatics in regulation of innate immunity. In addition, we have described the mode of action of recanalization of collecting lymphatics after excision of lymph node with special reference to clinical treatment for surgical removal of lymph nodes-mediated secondary lymphedema. Finally, we have addressed the possibility that primary tumor cells and/or metastatic carcinoma cells themselves release key chemical substances to develop environment suitable for micro-metastasis in sentinel lymph node.

B16-BL6 melanoma cells release inhibitory factor(s) of active pump activity in isolated lymph vessels

We investigated whether supernatant cultured with melanoma cell lines B16-BL6 and K1735 or the Lewis lung carcinoma cell line (LLC) can regulate lymphatic pump activity with bioassay preparations isolated from murine iliac lymph vessels. B16-BL6 and LLC supernatants caused significant dilation of lymph microvessels with cessation of pump activity. B16-BL6 supernatant produced dose-related cessation of lymphatic pump activity. There was no significant tachyphylaxis in the supernatant-mediated inhibitory response of lymphatic pump activity. Pretreatment with 3 x 10(-5) M N(omega)-nitro-L-arginine methyl ester (L-NAME) or 10(-7) M or 10(-6) M glibenclamide and 5 x 10(-4) M 5-hydroxydecanoic acid caused significant reduction of supernatant-mediated inhibitory responses. Simultaneous treatment with 10(-3) M L-arginine and 3 x 10(-5) M L-NAME significantly lessened L-NAME-induced inhibition of the supernatant-mediated response, suggesting that endogenous nitric oxide (NO) plays important roles in supernatant-mediated inhibitory responses. Chemical treatment dialyzed substances of <1,000 molecular weight (MW), producing complete reduction of the supernatant-mediated response. In contrast, pretreatment with heating or digestion with protease had no significant effect on supernatant-mediated response. These findings suggest that B16-BL6 cells may release nonpeptide substance(s) of <1,000 MW, resulting in significant cessation of lymphatic pump activity via production and release of endogenous NO and activation of mitochondrial ATP-sensitive K(+) channels.

Effects of leg rotation on lymph flow and pressure in rabbit lumbar lymph circulation: in vivo experiments and graphical analysis

The intraluminal lymphatic pressure in rabbit lumbar lymphatic trunks was determined. To estimate the lymphatic pressure, graphical analysis was performed from lymph outflow pressure-flow rate relationship and lymph infusion pressure-flow rate relationship. A direct measurement technique with a T-tube was also carried out to measure the pressure in the lumbar lymphatic. The rabbit leg was passively rotated at 0.3 Hz in the diameter of 8 cm to enhance the lymphatic pump activity of the leg. The estimated pressure and measured pressure in the lymphatics were 6.50 and 7.14 +/- 2.38 cmH2O, respectively. It was confirmed that similar values could be obtained from these two methods. The lymphatic pumping in the leg may affect a distribution of pressure in the lumbar lymphatic system.

Parathyroid hormone-related protein-(1-34) inhibits intrinsic pump activity of isolated murine lymph vessels

Parathyroid hormone-related protein (PTHrP) was originally found as a tumor-derived vasoactive factor and has also been known to produce significant relaxation of vascular smooth muscles. Thus effects of PTHrP-(1-34), a PTH receptor-binding domain, on spontaneous lymphatic pump activity was investigated in isolated pressurized lymph vessels of mice. Low concentrations (1 x 10(-10) and 3 x 10(-10) M) of PTHrP-(1-34) dilated lymph vessels and reduced the frequency of pump activity, whereas high concentrations (1 x 10(-9) to 1 x 10(-8) M) of PTHrP-(1-34) caused dilation with cessation of the lymphatic pump activity. N(omega)-nitro-L-arginine methyl ester (L-NAME; 3 x 10(-5) M) but not indomethacin (1 x 10(-5) M) significantly reduced the PTHrP-(1-34)-induced inhibitory responses of the lymphatic pump activity. In the presence of L-NAME (3 x 10(-5) M) and L-arginine (1 x 10(-3) M), the L-NAME-induced inhibition in the PTHrP-(1-34)-mediated responses was significantly reduced. Glibenclamide (1 x 10(-6) M) significantly suppressed the inhibitory responses of the lymphatic pump activity induced by PTHrP-(1-34) and S-nitroso-N-acetyl-penicillamine. The PTHrP-(1-34)-mediated inhibitory responses were significantly reduced by treatment with PTHrP-(7-34) (1 x 10(-7) M). These results suggest that PTHrP-(1-34) inhibits spontaneous pump activity of the isolated lymph vessels via PTH receptors and that production and release of endogenous nitric oxide and activation of ATP-sensitive K(+) channels in the lymph vessels contribute to the PTHrP-(1-34)-mediated inhibitory responses of the lymphatic pump activity.

[Lymphodynamic factors governing lymphatic spread of carcinoma cells]

Carcinoma frequently spreads and grows through the lymphatic system, whereas malignant tumors of mesenchymal origin more frequently spread via the hematogenous route. This paper reviews cancer spread with special reference to tumor microcirculation, vascular endothelial growth factor receptor (VEGFR)-3-mediated lymphangiogenesis, regeneration of collecting lymph vessels, and the role of nitric oxide in lymphatic metastasis. Oxygen and pH are key microenvironmental factors in the development and growth of tumors and their response to treatment. Thus the physiological and pathophysiological roles of hypoxia and acidic pH in the tumor microenvironment in lymphatic metastasis are demonstrated. Lymph angiogenesis in tumor tissues and regeneration of collecting lymph vessels with special reference to VEGFR-3 and its agonists VEGF-C/VEGF-D are discussed. The occurrence and biological significance of intratumoral lymph angiogenesis in breast cancer have been established. VEGF-C as a molecular link between tumor lymph angiogenesis and metastasis is identified. Finally, the role of nitric oxide (NO) in tumor microcirculation and lymphatic metastasis of carcinoma cells is evaluated.

Effects of diets enriched in n-6 or n-3 fatty acids on cholesterol metabolism in older rats chronically fed a cholesterol-enriched diet

Hypocholesterolemic effects in older animals after long-term feeding are unknown. Therefore, aged rats (24 wk of age) fed a conventional diet were shifted to diets containing 10% perilla oil [PEO; oleic acid + linoleic acid + alpha-linolenic acid; n-6/n-3, 0.3; polyunsaturated fatty acid/saturated fatty acid (P/S), 9.6], borage oil [oleic acid + linoleic acid + alpha-linolenic acid; n-6/n-3, 15.1; P/S, 5.3], evening primrose oil (EPO; linoleic acid + gamma-linolenic acid; P/S, 10.5), mixed oil (MIO; oleic acid + linoleic acid + gamma-linolenic acid + alpha-linolenic acid; n-6/n-3, 1.7; P/S, 6.7), or palm oil (PLO; palmitic acid + oleic acid + linoleic acid; n-6/n-3, 25.3; P/S, 0.2) with 0.5% cholesterol for 15 wk in this experiment. There were no significant differences in the food intake and body weight gain among the groups. The liver weight in the PEO (n-6/n-3, 0.3) group was significantly higher than those of other groups in aged rats. The serum total cholesterol and very low density lipoprotein (VLDL) + intermediate density lipoprotein (IDL) + low density lipoprotein (LDL)-cholesterol concentrations of the PLO (25.3) group were consistently higher than those in the other groups. The serum high density lipoprotein cholesterol concentrations of the PEO (0.3) and EPO groups were significantly lower than in the other groups at the end of the 15-wk feeding period. The liver cholesterol concentration of the PLO (25.3) group was significantly higher than those of other groups. There were no significant differences in the hepatic LDL receptor mRNA level among the groups. Hepatic apolipoprotein (apo) B mRNA levels were not affected by the experimental conditions. The fecal neutral steroid excretion of the PLO (25.3) group tended to be low compared to the other groups. The results of this study demonstrate that both n-6 fatty acid and n-3 fatty acids such as gamma-linolenic acid and alpha-linolenic acid inhibit the increase of serum total cholesterol and VLDL + IDL + LDL-cholesterol concentrations of aged rats in the presence of excess cholesterol in the diet compared with dietary saturated fatty acid.

Immunohistochemical detection of retinal cones in monkey retina: light and electron microscopic study

PURPOSE

Retinal cones have wave-length-specific visual pigments. To identify subclasses of cones, opsin-specific antibodies were previously established for the immunohistochemical studies of frozen sections. In this study, we produced retinal cone antibodies and examined (1) the specificity of these antibodies with Western blot analysis, (2) the application of these antibodies to paraffin-embedded monkey retinal sections, and (3) the use of these antibodies in light and electron microscopic immunohistochemical analyses of the localization of retinal cones.

METHODS

The N-terminal peptide of blue opsin, and the C-terminal peptide of green/red opsin were used as immunogens in New Zealand White rabbits. Immunohistochemical staining was performed using the ABC method and immunogold method. As antigen retrieval treatment, paraffin-embedded cynomolgus monkey retinas were subjected to enzyme and microwave treatment.

RESULTS

Both anti-red/green and anti-blue cone opsin antibodies detected 40 kDa native cone opsins in crude retina extract. The red/green and blue cone opsin immunostaining after trypsin treatment revealed that a positive signal was observed in the cone outer segment. Immunogold labeling also showed that gold particles were concentrated on the cone outer segment.

CONCLUSION

In the antigen retrieval method, trypsin treatment is the appropriate method to obtain optimal staining of paraffin sections of retina. Using this method, retinal cone in conserved old paraffin sections can be identified immunohistochemically.

Effects of VEGF on Ca(2+)-transient in cultured lymphatic endothelial cells and mechanical activity of isolated lymph vessels

We investigated the effects of vascular endothelial growth factor (VEGF(165)) on [Ca(2+)](i)-transient in cultured lymphatic endothelial cells (LEC) and mechanical activity of isolated dog thoracic ducts. VEGF (0.1-10 ng/ml) caused a dose-dependent increase of the [Ca(2+)](i) in LEC. Pretreatment with 10(-5) M genistein or 5x10(-6) M herbimycin A produced a significant reduction of the VEGF-induced [Ca(2+)](i)-transient. In the presence of 10(-6) M thapsigargin, VEGF caused no significant effect on the [Ca(2+)](i)-transient. Pretreatment with Ca(2+)-free solution containing 0.1 mM EGTA produced no significant effect on the peak increase of [Ca(2+)](i) induced by 0.1 or 10 ng/ml VEGF, but significantly depressed the sustained part of [Ca(2+)](i) observed at the higher concentration of VEGF. The VEGF (0.1-10 ng/ml) caused a significant dilation of the isolated lymph vessels with intact endothelium, which were precontracted with U46,619. The 10 ng/ml VEGF-induced dilation was significantly reduced by 3 x 10(-5) M N(omega)-nitro-L-arginine methyl ester (L-NAME). The action of L-NAME was inhibited by the simultaneous application of 10(-3) M L-arginine. Mechanical rubbing of the endothelium also caused significant inhibition of the VEGF-induced dilation. The findings suggest that VEGF(165) may activate the receptor-related tyrosine kinase and cause the release of Ca(2+) from the inositol 1,4, 5-triphosphate-sensitive intracellular Ca(2+) stores in LEC. VEGF(165) also produces endothelium-dependent nitric oxide-mediated dilation of the precontracted isolated lymph vessels.

Physiological roles of endogenous nitric oxide in lymphatic pump activity of rat mesentery in vivo

Physiological roles of endogenous nitric oxide (NO) in the lymphatic pump activity of rat mesenteries in vivo were evaluated using an intravital video microscope system. Changes in the pumping frequency (F), the end diastolic diameter (EDD), and the end systolic diameter (ESD) of the mesenteric lymph microvessels were measured with the microscope system and then the pump flow index (PFI) was calculated. A 15-min superfusion of 30 microM N(omega)-nitro-L-arginine methyl ester (L-NAME) in the mesenteries caused significant increases of F and PFI and a significant decrease of the EDD and ESD. Simultaneous superfusion of 1 mM L-arginine with 30 microM L-NAME produced a significant reversal of the L-NAME-mediated increase of F and decrease of ESD. A 15-min superfusion of 100 microM aminoguanidine caused no significant effects on F, EDD, and ESD of the mesenteric lymph vessels in vivo. These findings suggest that endogenous NO has physiologically modulated the lymphatic pump activity in rat mesentery in vivo and that the production and release of NO may be mediated by constitutive NO synthase but not by inducible NO synthase.

Development of an experimental apparatus for investigating lymphatic pumping activity of murine mesentery in vivo

The present study has been attempted to establish a modified intravital microscope system for investigating murine lymphatic pumping activity in vivo and evaluate whether or not there is rhythmic pumping activity of murine mesenteric lymphatic vessels in vivo. We designed and constructed a custom organ chamber with a semicircular channel (8 mm in radius, 5 mm in width, 3 mm in depth), being suitable for the superfusing of murine mesentery in vivo. A marked lymphatic pumping activity was observed in the mesenteries of DDY mice. The maximal and minimal diameter and frequency in the pumping activity were 60.9 +/- 1.0 microm, 53.7 +/- 1.8 microm and 12.8 min(-1) (n = 5), respectively. Both NE (norepinephrine, 10(-8)-10(-6) M) and TEA (tetraethylammonium, 1-10 mM) caused dose-dependent constriction of the mesenteric lymphatic vessels in the mice. These findings suggest that a modified intravital microscope system with a specially designed and constructed edge-monitoring device enables us to investigate in vivo lymphatic circulation in murine mesenteries.

Involvement of ATP-sensitive K(+) channels in spontaneous activity of isolated lymph microvessels in rats

Physiological roles of ATP-sensitive K(+) channels for spontaneous activity in isolated rat mesenteric lymph microvessels (maximum diameter approximately 80-150 microm) were investigated. The lymph microvessels were cannulated with glass micropipettes and pressurized at a perfusion pressure of 6 cmH(2)O. Changes in the diameter and frequency of spontaneous contractions in the lymphatics were measured with videomicroscopy. Pinacidil (K(+)-channel opener) inhibited the spontaneous activity. In the presence of glibenclamide (selective ATP-sensitive K(+)-channel blocker; 10(-7) and 10(-6) M) and tetraethylammonium (TEA; nonselective K(+)-channel blocker; 10(-4) and 10(-3) M), the pinacidil-induced inhibition of the spontaneous contractions in lymph microvessels was significantly reversed. Glibenclamide and TEA themselves, however, did not affect the frequency of spontaneous activity in the lymph microvessels. These results suggest that ATP-sensitive K(+) channels are involved in the regulation of spontaneous activity in the smooth muscles of isolated lymph microvessels of rat mesenteries.

Effects of endothelin on spontaneous contractions in lymph vessels

A mode of action of endothelin (ET) on spontaneous contractions was investigated in ring preparations of isolated bovine mesenteric lymphatics. ET-1 at concentrations between 10(-10) and 10(-9) M caused a dose-dependent increase in the frequency of spontaneous contractions. The specific ET(A)-receptor antagonist BQ-123 (5 x 10(-7) M) caused a significant inhibition of the ET-1-induced positive chronotropic effect in the ring preparations with and without the endothelium. Mechanical denudation of the lymphatic endothelial cells produced a significant potentiation of the ET-induced positive chronotropic effect. BQ-3020 (10(-8)-10(-7) M), a selective ET(B)-receptor agonist, induced dose dependently negative chronotropic and inotropic effects on the spontaneous contractions in the ring preparations with intact endothelium. Mechanical removal of the endothelium caused a significant reduction of the BQ-3020-induced negative chronotropic and inotropic effects. The ET-1-induced positive chronotropic effect was potentiated by pretreatment with N(omega)-nitro-L-arginine methyl ester (L-NAME) (10(-5) M) but unaffected by aspirin (10(-5) M). Additional treatment with L-arginine (10(-4) M) completely reversed the L-NAME-mediated potentiation of the ET-induced chronotropic effect. These results suggest that stimulation of ET(A) receptors on the lymphatic smooth muscles causes a positive chronotropic effect on the spontaneous contractions, and stimulation of ET(B) receptors on the lymphatic endothelial cells induces a release of nitric oxide, which results in the chronotropic and inotropic effects on spontaneous contractions in isolated bovine mesenteric lymphatics.

Human perspiration measurement

We review various methods developed for human perspiration measurement and their physiological applications, with special reference to the performance and application of a new home-made ratemeter and instrumentation with a microscope. Many kinds of humidity sensor based on humidity-sensitive electrical properties have been investigated and placed on the market. Recently a capacitive thin-film humidity sensor was constructed and confirmed to be one of the best humidity sensors for accurately and quickly detecting changes in the relative humidity of gas-flow perfused through a ventilated chamber for human perspiration measurement. In this paper we also introduce a new home-made ratemeter with a capacitive humidity sensor, the electrical output of which is not disturbed by changes in ambient temperature, and new instrumentation for directly observing drops of sweat secreted from eccrine glands in human skin and simultaneously measuring the change in amount of perspiration at the same area of skin. Finally, we review physiological applications of the methods for measuring human palmar perspiration including emotional sweating.

Electrical stimulation-induced alpha1- and alpha2-adrenoceptors-mediated contraction in isolated dog thoracic ducts

The electrical stimulation-induced responses of isolated dog thoracic ducts were investigated using an organ bath technique. Electrical stimulation (0.7 ms in pulse width, 25 V in nominal voltage, 10 s in duration time, 1-32 Hz at frequency) produced frequency-related contractions in the lymphatic preparations. The contractions were abolished by pretreatment with tetrodotoxin (10(-7) M), guanethidine (10(-7), 10(-6) M), and bretylium (10(-7), 10(-6) M). Cocaine (10(-6) M) significantly potentiated the electrical stimulation-induced contractions. Phentolamine (10(-8)-10(-5) M), prazosin (10(-8)-10(-5) M), bunazosin (10(-6), 10(-5) M), yohimbine (10(-8)-10(-6) M) and rauwolscine (10(-8)-10(-6) M) also dose-dependently reduced the contractions. On the other hand, propranolol (10(-8)-10(-6) M), atropine (10(-6) M), hexamethonium (10(-6) M), aspirin (3 x 10(-5) M), N(omega)-nitro-L-arginine methyl ester (L-NAME) (3 x 10(-5) M) and L-NAME (3 x 10(-5) M) + L-arginine (10(-4) M) caused no significant effect on electrical stimulation-induced contractions. No significant difference in the electrical stimulation-induced responses was observed between the lymphatic preparations with and without an intact endothelium. The electrical stimulation caused only a small contraction with no relaxation in the thoracic duct preparation precontracted with 10(-8) M U46619. The small contraction was abolished by 10(-5) M phentolamine. These findings suggest that there exists alpha1- and alpha2-adrenoceptors-mediated excitatory innervation, but no NO-ergic inhibitory nerve fiber in dog thoracic ducts.

Flow- and agonist-mediated nitric oxide- and prostaglandin-dependent dilation in spinal arteries

Isolated rabbit spinal resistance-sized arteries (approximately 100 microns in diameter and approximately 3 mm long) were cannulated at both ends with glass micropipettes and perfused at constant pressure (60 mmHg). An increase of flow rate corresponding to a change of pressure gradient (delta P) ranging from 0 to 20 mmHg produced a flow-dependent vasodilation. Treatment with 50 microM aspirin or 10 microM indomethacin produced a significant reduction of the flow-dependent vasodilation only at delta P of 5 mmHg. In contrast, treatment with N omega-nitro-L-arginine methyl ester (L-NAME, 30 microM) produced no significant change. In the presence of 10 microM indomethacin, however, 30 microM L-NAME caused a marked decrease in the arterial diameter at delta P of 5 mmHg, which was completely reversed with additional administration of 1 mM L-arginine. Acetylcholine (ACh) produced a dose-dependent increase in the arterial diameter. The ACh-induced vasodilation was significantly reduced by 10 microM indomethacin or 50 microM aspirin and partially suppressed by 30 microM L-NAME. Pretreatment with both indomethacin and L-NAME completely reduced the ACh-induced vasodilation. In the presence of 10 microM indomethacin, additional treatment with 1 mM L-arginine significantly reversed the L-NAME-induced inhibition of the ACh-mediated vasodilation. Endothelial removal with Triton X-100 significantly reduced the ACh-induced vasodilation. Isocarbacyclin (a stable prostaglandin I2 analogue), prostaglandin E2, and arachidonic acid caused a dose-dependent dilation in the small arteries. These findings suggest that prostanoids play a major role in the flow- or ACh-induced vasodilation in the rabbit spinal resistance-sized small arteries.

Capsaicin-induced nitric-oxide-dependent relaxation in isolated dog urethra

Capsaicin (5 x 10[-8] to 5 x 10[-5] M) produced a non-adrenergic and non-cholinergic phasic relaxation in a concentration-dependent manner in isolated dog urethral preparations precontracted by noradrenaline. The mode of action of capsaicin was investigated with special reference to the possible involvement of endogenous nitric oxide (NO). A marked tachyphylaxis was observed in the responses to capsaicin. Pretreatment with NG-nitro-L-arginine-methyl-ester (L-NAME) prevented or markedly reduced the inhibitory effect of L-NAME. Methylene blue inhibited the capsaicin-induced relaxation. In preparations stored at 4 degrees C for 72 h, the reduction in the capsaicin-induced relaxation was significantly greater than that in the relaxation induced by either electrical field stimulation or by sodium nitroprusside. We conclude that capsaicin produces an endogenous-NO-dependent relaxation in the isolated dog urethra via mechanisms that deteriorate during cold storage of the preparations.

Inhibitory effects of fluorescein isothiocyanate photoactivation on lymphatic pump activity

The effects of photoactivation of fluorescein 5'-isothiocyanate (FITC)-dextran on lymphatic pump activity of rat mesenteric collecting vessel were studied in vivo. Rats were anesthetized with intraperitoneal alpha-chloralose and urethane, and the mesenteries were studied by using intravital videomicroscopic techniques. The diameter of the collecting lymph vessels were continuously monitored and lymphatic pump parameters (end diastolic diameter, end systolic diameter, stroke volume index, ejection fraction, contraction frequency, and pump flow index) were calculated. FITC-dextran (42 nmol/100 g body wt) without illumination caused no disturbance of lymphatic pump activity. Photoactivated FITC-dextran significantly increased end systolic diameter and decreased stroke volume index, ejection fraction, contraction frequency, and pump flow index. End diastolic diameter was not changed throughout the experiment. Superoxide dismutase (120 U/ml) and catalase (5000 U/ml) had no protective effect on photoactivated FITC-induced pump dysfunction, while histidine (singlet oxygen quencher, 10 mM) significantly prevented the disturbance of pump parameters. These results indicate that photoactivation of FITC induces negative chronotropic and negative inotropic effects in lymphatic pump activity through generation of singlet oxygen in the mesentery.

Macrophage-induced nitric oxide and prostanoid dependent relaxation of arterial smooth muscles

We have studied mechanisms of vasodilation induced by supernatant fluid of rat macrophages (Mø), using an arterial bioassay preparation. The cells emigrated by an intraperitoneal injection of thioglycollate were isolated and cultured for 12 h in RPMI 1640 medium with and without 2.0 mM L-arginine. More than 98% of the isolated cells clearly demonstrated Wright's esterase staining and phagocytosis of acetylated low-density lipoprotein. The bioassay preparation was made of dog isolated femoral arteries with and without the endothelium. The supernatant of macrophages cultured in the L-arginine-free RPMI 1640 caused a significant reduction of the precontraction in the bioassay rings, being approximately 51.6-66.7% of sodium nitroprusside (SNP) induced maximum vasodilation in each ring. The supernatant of macrophages cultured in the RPMI 1640 containing 2.0 mM L-arginine produced a significantly smaller relaxation (approximately 32.3-33.3%). The Mø-induced vasodilation was significantly inhibited by the coculture of the macrophages with 1 microM dexamethasone, 10 microM cycloheximide, 50 microM N omega-nitro-L-arginine methyl ester (L-NAME), 10 microM indomethacin, or 10 microM aspirin. The L-NAME-induced inhibition was significantly reversed by an additional treatment with 100 microM L-arginine. The coculture with both L-NAME and indomethacin caused a reduction of the Mø-induced vasodilation (approximately 12.5-13.4%) similar to reductions produced by dexamethasone (approximately 10.8-12.1%) and cycloheximide (approximately 11.4-12.4%). Coculture with 10 micrograms/mL bacterial lipopolysaccharide caused a slight facilitation of the Mø-induced vasodilation (approximately 78.2-79.6%). These findings suggest that supernatant fluid of rat exuded macrophages cultured with low concentrations of L-arginine causes an endogenous nitric oxide (NO) and vasodilative prostaglandin dependent relaxation of arterial smooth muscles.

Instrumentation of a handy microscopic probe for concurrent observation and measurement of active sweat secretion, and its applications

Instrumentation for the concurrent, dynamic monitoring of active sweat glands and perspiration volume is described. A device for the measurement of the rate of sweat secretion was installed on the head part of a microscope. The combined apparatus (microscopic probe) is handy for use and its weight is very light (ca. 300 g). The microscopic probe is easily attached to the surface of human skin. The dynamic activities of the sweat glands on the forehead and nose and under the nose were observed and measurement when thermal, mental and physical stimuli were applied. The activities of individuals sweat glands were asynchronous when observed in units of a few seconds or less; however, they worked synchronously in a unit period of several seconds. The latter were recorded as fine peaks by a strip chart recorder. The proposed system may be useful for the study of the sympathetic nervous system, the skin sympathetic reflex and the working of sudomotor nerves.

5-Hydroxytryptamine-induced endothelium-dependent and -independent relaxations in isolated dog anterior spinal small arteries

The mode of action of 5-hydroxytryptamine (5HT) was investigated in isolated dog anterior spinal small arteries. Lower concentrations of 5HT (10(-9)-10(-7) M) caused a dose-dependent contraction and higher concentrations (10(-6)-10(-3) M) produced a dose-dependent relaxation of the arteries precontracted by 10(-7) M U 46619. The 5HT-induced relaxation was significantly antagonized by methiothepin (10(-9)-10(-6) M). Ketanserin (10(-6) M) and ICS 205-930 (3 x 10(-6) M) did not affect the 5HT-induced relaxation of the arteries. The relaxant response to 5HT was reduced significantly by mechanical rubbing of the endothelial cells. The 5HT-induced endothelium-independent relaxation was also antagonized significantly by methiothepin (10(-6) M). Aspirin (5 x 10(-5) M) or N omega-nitro-L-arginine methyl ester (L-NAME) (10(-6) M) significantly suppressed the 5HT-induced endothelium-dependent relaxation. L-Arginine (10(-3) M) also significantly reversed the L-NAME induced reduction of the 5HT-induced endothelium-dependent relaxation. Treatment with L-NAME in the presence of aspirin also produced much greater reduction of the 5HT-induced endothelium-dependent relaxation. Isocarbacyclin (10(-9)-10(-5) M) induced a concentration-dependent relaxation of the isolated spinal small arteries precontracted by 10(-7) M U 46619. These results suggest that 5HT induces endothelium-dependent and -independent relaxations of the isolated anterior spinal small arteries mainly via activation of 5HT1-like receptor and that endogenous nitric oxide and vasodilative prostaglandins may contribute to the 5HT-induced endothelium-dependent relaxation of the arteries.

The primary structure of the Cl(-)-translocating ATPase, b subunit of Acetabularia acetabulum, which belongs to the F-type ATPase family

The genes possibly encoding the b subunit (50 kDa) of the Cl(-)-translocating ATPase of Acetabularia acetabulum were cloned from total RNA and from poly(A)+ RNA and sequenced. The deduced amino acid sequence of the open reading frame consisted of 478 amino acids and showed high similarity to the beta subunit of chloroplast F1-ATPase. Gene fragments encoding the putative beta subunit of chloroplast F1- (273 bp) and mitochondrial F1-ATPases (332 bp) were also cloned from A. acetabulum and sequenced, respectively. The deduced amino acid sequence of the chloroplast F1-ATPase showed 92.5% identity to be primary structure of the b subunit of the Cl(-)-translocating ATPase, while the nucleotide sequences were 79.9% identical. The deduced amino acid sequence of the latter was 77.3% identical to that of the b subunit of the Cl(-)-translocating ATPase and the nucleotide sequences were 67.5% identical. By Northern analysis, these three beta-like genes were demonstrated to be transcribed with different sizes of RNA species. A putative chloroplast F1-beta fragment also hybridized with chloroplast DNA isolated from the organism.

[A new helical CT approach with ECG gated reconstruction]

We proposed a new helical CT approach with ECG-gated reconstruction for obtaining high quality 2D, 3D, and 4D images. Original helical images were acquired with a single helical scan with overlapping reconstruction and ECG information. Post-processing to improve temporal resolution and 4D volume set reconstruction were performed, and 2D, 3D and 4D displays were obtained. Using this new method, 2D and 3D images without cardiac motion artifacts were obtained by selecting images in diastolic phase. 2D images with cardiac motion were obtained using images of the same position and different cardiac phases. Finally, 4D images (3D images with phase information) were obtained.

Acetylcholine- and flow-induced production and release of nitric oxide in arterial and venous endothelial cells

To study flow-mediated responses in a conduit vein, we investigated the physiological characteristics of endothelium-dependent acetylcholine (ACh)- and flow-induced relaxations using a conventional bioassay cascade. Cylindrical segments isolated from canine common carotid arteries and external jugular veins were perfused at a constant mean flow rate ranging from 1 to 8 ml/min. Endothelium-derived nitric oxide (NO) activity in perfusion effluent through the arterial and venous segments was measured by relaxation of endothelium-denuded arterial rings and arterial and/or venous rings precontracted by prostaglandin F2 alpha, respectively. Stimulation by a flow rate of 8 ml/min on the arterial and venous endothelial cells produced approximately 60 and 20% of the maximum relaxation in the arterial and venous rings, respectively. ACh (10(-6) and 10(-5) M) perfused through the arterial and venous segments with endothelium caused dose-related relaxations of both bioassay rings. The ACh- and flow-induced relaxations were completely reduced by mechanical removal of the endothelial cells. Pretreatment with 5 x 10(-5) M NG-nitro-L-arginine methyl ester (L-NAME) produced a significant reduction of the ACh- and flow-induced vasodilation. Additional treatment with 10(-4) M L-arginine significantly reversed the L-NAME-induced inhibition of ACh-induced relaxation but had no effect on flow-induced relaxation. When the flow rate was increased from 2 to 4 ml/min, the same concentrations of ACh produced larger dose-related relaxations than those obtained at a flow rate of 2 ml/min. Pretreatment with 25 U/ml superoxide dismutase caused no significant effect on the flow-mediated potentiation of ACh-induced relaxation. These findings suggest that venous endothelial cells of canine large vein are able to produce and release NO by stimulation of increased flow or ACh to a significantly lesser extent compared with the artery and that ACh-induced vasodilation is potentiated by an increase in shear stress up to approximately 4 dyn/cm2 loaded on the endothelial cells.

5-Hydroxytryptamine-induced NO-dependent relaxation in isolated strips of monkey popliteal lymph nodes

5-Hydroxytryptamine (5-HT, 0.01-100 microM) and 5-carboxamidotryptamine (5-CT, 0.001-10 microM) produced dose-related relaxations in strips cut from monkey popliteal lymph nodes precontracted with a perfusion of Krebs bicarbonate solution containing 80 mM KCl. These 5-HT agonists caused no significant effect on the basal tone of the lymph node strips. The 5-HT-induced relaxation is competitively antagonized by pretreatment with a selective 5-HT1-like receptor antagonist, methiothepin (0.01-0.1 microM). Schild plot analysis showed that the pA2 value and slope of methiothepin against 5-HT were 8.80 +/- 0.11 and 0.99 +/- 0.07 (n = 6), respectively. Pretreatment with methysergide (0.01-0.1 microM) significantly attenuated the 5-HT-induced relaxation of the strips. On the other hand, treatment with ketanserin (0.01-0.1 microM) and ICS-205-930 (0.01-0.1 microM) caused no significant effect on the 5-HT-or the 5-CT-induced relaxation. The 5-HT-induced relaxation was significantly reduced by 10 microM NG-monomethyl-L-arginine, which was reversed by 1 mM L-arginine. The relaxation in the lymph node strips was also significantly reduced by treatment with 10 microM methylene blue but not with 30 microM aspirin. These results suggest that 5-HT1-like receptors exist in the monkey popliteal lymph nodes. Stimulation of these receptors produces an endogenous nitric oxide (NO)-dependent relaxation in lymph node smooth muscle through an activation of cytosolic guanylate cyclase in the cells.

Histopathological features of atrophic thyroiditis with blocking type-TSH binding inhibitor immunoglobulins

To investigate the histopathological features of atrophic thyroiditis (AT) with blocking type-TSH binding inhibitor immunoglobulins (TBII), the present morphological observations were carried out employing additional immunohistochemical procedures. Moreover, these were compared with examples of goitrous Hashimoto's thyroiditis showing negative TBII (HT). There exist apparent differences between AT and HT. In particular, significant follicular atrophy with epithelial flattening including decreased positive staining of the follicular epithelial cells for thyroglobulin in AT was characteristically observed. These results suggest that the mechanism for the development of hypothyroidism in AT with blocking type-TBII might be due to suppression of thyroid cell function through the inhibition of endogenous TSH stimulation by the blocking antibody with subsequent epithelial degenerative destruction.

Histamine H2 receptor-mediated endothelium-dependent relaxation in canine spinal artery

The mechanisms of histamine-induced relaxation were investigated in isolated canine spinal branches of intercostal artery (SBICA). Histamine (10(-7) to 10(-4)M) and dimaprit (3 x 10(-6) to 3 x 10(-4)M) produced concentration-dependent relaxation in the SBICA which had been contracted by 5 x 10(-6)M norepinephrine, whereas 2-pyridylethylamine caused only a very small relaxation. The histamine- and dimaprit-induced relaxation were inhibited by famotidine but not by diphenhydramine. In the SBICA without endothelium, histamine elicited very little relaxation. Aspirin (5 x 10(-5)M) and AA 861 (10(-5)M) did not affect the histamine-induced relaxation. Treatment with L-NMMA (3 x 10(-5)M) or methylene blue (10(-5)M) significantly suppressed the acetylcholine-induced relaxation of the SBICA but not the histamine-induced one. These results suggest that histamine produces relaxation in the isolated canine SBICA through stimulation of H2-receptors on the endothelium. The relaxing mediator(s) released by histamine seems to be neither endogenous prostaglandins, lipoxygenase products, nor nitric oxide.

Purification and characterization of a membrane-bound ATPase from Acetabularia cliftonii that corresponds to a Cl(-)-translocating ATPase in Acetabularia acetabulum

A Mg(2+)-ATPase was solubilized from membranes of Acetabularia cliftonii using nonanoyl-N-methylgluconamide and purified by ion-exchange and gel permeation chromatography. One active ATPase fraction after Mono Q chromatography had a specific activity of 10 units/mg of protein. Judged from subunit composition [54 (a), 50 (b) with a fainter band around 40 kDa], catalytic properties, and N-terminal amino acid sequence of the b subunit, the isolated enzyme was comparable to the Cl(-)-ATPase of Acetabularia acetabulum. Immunological characterization of both subunits showed significant similarity to the F type of ATPase. Cl(-)-transport activity was observed by reconstitution studies into liposomes.

5-Hydroxytryptamine-2 and -4 receptors located on bovine isolated mesenteric lymphatics

Effects of 5-hydroxytryptamine (5-HT) agonists were investigated in the bovine isolated mesenteric lymphatics, and then the 5-HT receptor subtypes in the responses were pharmacologically classified by use of several 5-HT antagonists. Addition of 5-HT and that of alpha-methyl-5-hydroxytryptamine (alpha-methyl-5-HT) both produced concentration-dependent contractions in the presence of 3 x 10(-6) M [(1 alpha H, 5 alpha H)-8-methyl-8-azabicyclo(3.2.1)oct-3 alpha-yl]1H-indole-3-carboxylate hydrochloride, whereas 5-carboxamidotryptamine (5-CT) and 2-methyl-5-hydroxytryptamine (2-methyl-5-HT) caused no, or only slight, contraction in the lymphatics. Pretreatment with ketanserin caused a significant shift to the right in the concentration-response curve for 5-HT or alpha-methyl-5-hydroxytryptamine. Schild plot analyses showed that the pA2 values for ketanserin against 5-HT and alpha-methyl-5-hydroxytryptamine were 8.75 and 8.68, respectively. In contrast, 5-CT, 5-HT and metoclopramide caused concentration-dependent relaxations in the presence of 10(-6) M ketanserin in the lymph vessels after contraction with prostaglandin F2 alpha. 2-Methyl-5-HT up to 10(-4) M did not produce any relaxation. High concentrations of [(1 alpha H, 5 alpha H)-8-methyl-8-azabicyclo(3.2.1)oct-3 alpha-y1]1H-indole-3-carboxylate hydrochloride induced a significant inhibition of the 5-CT- and 5-HT-induced relaxation, but methiothepin and methysergide up to 10(-6) M and mechanical rubbing of the endothelium had no significant effect on the relaxation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of isocarbacyclin, a stable prostacyclin analogue, on monkey isolated cerebral and peripheral arteries

1. The effects of isocarbacyclin (TEI 7165), a stable prostacyclin analogue, were examined in monkey isolated cerebral and peripheral arteries. 2. Addition of TEI 7165 (0.1 nM-10 microM) produced a dose-dependent relaxation in cerebral arteries pre-contracted with 1 microM 5-hydroxytryptamine (5-HT). High concentrations (more than 1 microM) of TEI 7165 elicited a transient contraction followed by a sustained relaxation. 3. TEI 7165 also elicited a dose-dependent relaxation in the peripheral (except popliteal) arteries. The maximum relaxation induced by 10 microM TEI 7165 was greater (P < 0.05) in the mesenteric artery than in the cerebral artery. The negative logarithm of the EC50 value for the mesenteric, 7.6 +/- 0.3, was greater (P < 0.05) than that for the cerebral artery, 6.4 +/- 0.3. The decreasing order of potency for the TEI 7165-induced relaxation was as follows: mesenteric > renal > cerebral > coronary > popliteal. 4. Removal of the endothelium did not significantly affect TEI 7165-induced relaxations. 5. The transient contraction produced by high concentrations of TEI 7165 was not observed in cerebral arteries precontracted with 1 nM U46619, a stable analogue of thromboxane A2 (TXA2). Furthermore, the TEI 7165-induced contraction was markedly suppressed (P < 0.05) by treatment with 10 nM S1452, a TXA2 blocking agent. 6. These results suggest that TEI 7165 causes an endothelium-independent relaxation in monkey cerebral and peripheral arteries, and that there is a marked regional difference in the TEI 7165-induced relaxations. A high concentration of TEI 7165 also produces a transient contraction which is probably through activation of TXA2 (TP-) receptors.

Effects of vasoactive substances on the pig isolated hepatic lymph vessels

The present study examined the responses of isolated pig hepatic lymph vessels to vasoactive substances, the classification of alpha adrenoceptors and the mode of action of acetylcholine (ACh) with special reference to the lymphatic endothelial cells. Contractions of the hepatic lymph vessels were induced by norepinephrine (NE), epinephrine, prostaglandin F2 alpha, histamine and 5-hydroxytryptamine in a dose-dependent manner. NE was the most potent vasoconstrictor agent. 5-bromo-6[2-imidazolin-2-ylamino]-quinoxaline, xylazine and clonidine also produced dose-dependent contractions. NE-induced contractions were inhibited significantly by yohimbine (10(-8)-10(-6) M) but not by prazosin (10(-8)-10(-6) M). Pretreatment with yohimbine (10(-8)-10(-7) M) or rauwolscine (10(-8)-10(-7) M) caused a parallel shift to the right of the dose-response curve for 5-bromo-6[2-imidazolin-2-ylamino]-quinoxaline. These results suggest that the NE-induced contraction in pig hepatic lymph vessels seems to be mediated mainly through stimulation of alpha-2 adrenoceptors. ACh, isoproterenol, histamine, 5-hydroxytryptamine, ATP and adenosine caused dose-dependent relaxations in the hepatic lymph vessels precontracted by 5 x 10(-6) M prostaglandin F2 alpha. ACh was the most potent vasorelaxant agent. Pretreatment with atropine (10(-9)-10(-7) M) inhibited the ACh-induced relaxation in a competitive manner. Removal of endothelium caused a significant reduction of the ACh-induced relaxation. The ACh-induced relaxation was suppressed by pretreatment with N omega-nitro-L-arginine methyl ester (3 x 10(-5) M) and methylene blue (10(-5) M) but was unaffected by aspirin (10(-5) M).(ABSTRACT TRUNCATED AT 250 WORDS)

Chloroplast ATPase in Acetabularia acetabulum: purification and characterization of chloroplast F1-ATPase

ATPases were isolated from chloroplasts of the unicellular marine alga Acetabularia acetabulum. Two preparations of ATPase, a chloroplast-enriched fraction and an alpha beta gamma-complex were compared. The alpha beta gamma-complex was released into an EDTA solution and purified by anion-exchange chromatography, hydrophobic chromatography, and gel permeation chromatography. The subunit composition of this enzyme appeared to be 52-53 (alpha), 51 (beta), and 40 (gamma) kDa from SDS-PAGE. ATPase activity was enriched about 260-fold to a specific activity of approximate 4.1 U.mg protein-1. The catalytic properties of the alpha beta gamma-complex were as follows: pH optimum at 7.5; substrate specificity, ATP > ITP, GTP > UTP = CTP (Km for ATP 0.2 mM); divalent cation requirement, Mg2+ = Mn2+ = Co2+ > Zn2+ > Ni2+ > Ca2+; ATPase activity was inhibited by monovalent anions (NO3-, SCN-), while monovalent cations had neither inhibitory nor stimulatory effect. Orthovanadate had no inhibitory effect on the enzyme activity of alpha beta gamma-complex. Azide was the most effective inhibitor of the alpha beta gamma-complex. N-Terminal amino acid sequences of the alpha and beta subunits were not obtained and appeared to be blocked. The gamma subunit gave a sequence of AGLKEMKD-XIGSVXNTKKI, which showed 60% similarity to the gamma subunits of spinach and Chlamydomonas reinhardtii CF1-ATPase and EF1-ATPase.

Acetylcholine-induced endothelium-independent relaxations in monkey isolated superior and inferior caval veins

1. We examined the effects of acetylcholine (ACh), isoprenaline (Isop) and Ca-ionophore, A23187 on monkey isolated superior (SCV) and inferior caval veins (ICV) with and without intact endothelium, which had been partially contracted by 2 x 10(-6)-5 x 10(-6) M prostaglandin F2 alpha (PGF2 alpha). 2. Low concentrations of ACh (10(-10)-10(-9) M) produced a dose-dependent relaxation in the precontracted venous segments with endothelium. ACh at concentrations more than 10(-7) M elicited a transient contraction followed by a relaxation in these segments. 3. An addition of 5 x 10(-7) M A 23187 induced about 60% of maximum relaxation produced by 10(-5) M sodium nitroprusside (SNP) in each venous segment with endothelium. 4. Isop (10(-10)-10(-5) M) caused a dose-related relaxation in the precontracted caval veins with intact endothelium. 5. Removal of endothelium caused no significant effect on the ACh-induced dual responses but a significant inhibition of the A23187-induced relaxation. 6. Pretreatment with atropine antagonized competitively the ACh-induced relaxations in the endothelium-intact and endothelium-denuded caval veins. The Schild plot analysis showed that the pA2 values of the segments with and without endothelium were 9.72 +/- 0.14 (n = 5) and 10.01 +/- 0.23 (n = 6) in the ICV; and 9.95 +/- 0.20 (n = 5) and 9.70 +/- 0.10 (n = 5) in the SCV, respectively. 7. Pretreatment with 5 x 10-5M aspirin, 3 x 10-5M N0-nitro-L-arginine methylester, 1 mM tetraethylammonium,or 3 x 10-6 M glibenclamide caused no significant effect on the basal tone, ACh induced transient contraction, and ACh;.induced relaxation in the precontracted venous segments with and without endothelium.8. Pretreatment with 10-5 M methylene blue produced a significant reduction of the ACh- and SNP induced relaxations in the precontracted venous segments with and without endothelium. The pretreatment with the same concentration of methylene blue, however, caused no significant effect on the Isop-induced relaxation in venous segments with endothelium.9. The results suggest that ACh acts directly on the venous smooth muscle cells via a high-affinity muscarinic receptor subtype to accumulate cellular cyclic GMP producing endothelium-independent relaxation in the monkey caval veins.

Effects of collagenase, elastase, and hyaluronidase on mechanical properties of isolated dog jugular veins

To study the contribution of tissue components to the mechanical properties of veins, pressure-volume relationships were obtained with the cylindrical segments of isolated dog external jugular veins at several levels of longitudinal extension. At each length, the transmural pressure of the segment was raised up to 20 cmH2O and then reduced to 0 cmH2O by increasing and decreasing the intraluminal volume at a constant rate. The longitudinal extension of the venous segments caused a significant reduction in the incremental volume elasticity within the pressure range of 0-2 cmH2O (E0-2) as well as a significant increase of the incremental volume elasticity within 10-20 cmH2O (E10-20). The pressure-volume relationships of venous segments were also constructed in the same way after treatment with 1 mg/ml collagenase for 30 min, 0.1 mg/ml elastase for 5 min, or 1 mg/ml hyaluronidase for 60 min. Treatment with collagenase or elastase produced a significant increase of the E0-2. The treatment, however, caused no effect on E10-20. Treatment with hyaluronidase induced no effect on these mechanical parameters but produced a significant attenuation of the extension-induced decrease in E0-2. Activation of the venous smooth muscles induced by norepinephrine (10(-4) M) or high-potassium Krebs solution caused a significant decrease of E0-2 as well as a significant increase of E10-20. A complete relaxation of the smooth muscles elicited by Ca(2+)-free Krebs solution containing ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (2 mM) caused an increase of E0-2. Mechanical rubbing of the endothelium caused no significant effect on E0-2 and E10-20.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of acetylcholine on spontaneous contractions in isolated bovine mesenteric lymphatics

The effects of acetylcholine (ACh) on spontaneous contractions in isolated bovine mesenteric lymph vessels were investigated. ACh ranging from 3 x 10(-8) M to 10(-5) M produced dose-dependent negative chronotropic and inotropic effects on the spontaneous contractions. In the lymph vessels without endothelium, ACh at the same concentration range had no significant effect on the spontaneous contractions. Atropine (10(-9) and 10(-8) M) caused a parallel shift to the right of the dose-chronotropic response curve for ACh. The pA2 value of atropine to ACh in the negative chronotropic effect was 8.90 +/- 0.20 (n = 6). Aspirin (10(-5) M) produced no significant inhibition of the ACh-induced negative chronotropic and inotropic effects. NG-monomethyl-L-arginine (L-NMMA; 3 x 10(-5) M) significantly suppressed the ACh-induced negative responses on spontaneous contractions. In the same lymphatic segments, L-arginine (10(-4) M) reversed completely the inhibition by L-NMMA of the ACh-induced responses. These results suggest that low concentrations of ACh produce negative chronotropic and inotropic effects on spontaneous contractions in bovine mesenteric lymphatics and that the responses may be mediated by nitric oxide or its related compound released from the endothelial cells through activation of low-affinity muscarinic receptors.

Interstitial nephritis associated with glomerulonephritis in a patient with Hashimoto's disease and idiopathic portal hypertension

A middle-aged women with hypothyroidism, idiopathic portal hypertension and nephrotic syndrome is presented. This unusual clinical appearance could not be explained as SLE by serological examinations. Pathohistological examinations showed "Banti's liver", Hashimoto's thyroiditis and diffuse proliferative glomerulonephritis with severe tubulo-interstitial nephritis. Immunohistochemical studies revealed IgA deposits in glomeruli. Electron microscopic study disclosed peculiar lucent areas of rarefaction with osmiophilic particles in tubular basement membranes. This tubulointerstitial nephritis was considered to be related to the immunological mechanism involving thyroid gland, liver and kidney disorders. This case thus had a clinically rare combination of these three.

Improvement of reconstitution of the Cl(-)-translocating ATPase isolated from Acetabularia acetabulum into liposomes and several anion pump characteristics

The improved reconstitution of the Mono Q-III fraction, a Cl(-)-translocating ATPase, isolated from Acetabularia acetabulum (Ikeda et al. (1990) Biochemistry 29, 2057-2065) into liposomes rendered transport properties of this enzyme clear. The liposomes were prepared by the reversed-phase method using egg lecithin and cholesterol in a molar ratio of 2:1 and the purified ATPase was incorporated into the liposomes by a dialysis for 3 h. About 80% of the ATPase was incorporated into the liposomes. The weight ratio of the enzyme to lipid was 1:400-600. A sigmoid curve was obtained when the Cl(-)-transport activity of the enzyme was plotted against Cl- concentration. Hill's plot afforded a half-substrate concentration [S]0.5 of 45 mM and a Hill's coefficient n of 2.33. Effects of Br- and F- on the Cl(-)-transport were also examined in the reconstituted system, both halide ions decreased the 36Cl- efflux significantly. These kinetic data are in good agreement with the electrophysiological data presented by Tittor et al. ((1983) J. Membr. Biol. 75, 129-139).

Effects of aortic pressure and vasoactive agents on the vascular resistance of the vasa vasorum in canine isolated thoracic aorta

1. We have developed a new preparation for continuously measuring changes in vascular resistance of the vasa vasorum of the canine isolated thoracic aorta perfused at a constant flow rate with Krebs-bicarbonate solution. 2. An increase of more than 150 mmHg in aortic pressure caused a significant increase in the vascular resistance of the vasa vasorum. 3. 5-Hydroxytryptamine (5-HT), noradrenaline (NA), adrenaline and dopamine caused dose-dependent increases in the vascular resistance of the vasa vasorum. The decreasing order of potency in the vasoconstrictor responses was as follows: 5-HT >> NA = adrenaline >> dopamine. The 5-HT- and adrenaline-induced vasoconstrictor responses were inhibited by methysergide and by phentolamine plus propranolol, respectively. 4. Acetylcholine (ACh), isoprenaline (ISP), histamine (His), ATP, ADP and adenosine produced dose-related decreases in the vascular resistance of aortic vasa vasorum perfused with the Krebs solution containing 10(-5) M-NA. The decreasing order of potency in the response was as follows: ACh = ISP > His >> adenosine = ATP = ADP. The ACh-, ISP- and His-induced vasodilator responses were antagonized by atropine, propranolol and famotidine, respectively. 5. The results suggest that the preparation described is useful for studying the regulation of vascular resistance of aortic vasa vasorum and that aortic pressure and vasoactive compounds may directly regulate the vascular resistance of the vasa vasorum in canine isolated thoracic aorta.

Time-dependent potentiation of contractile response to norepinephrine in canine isolated cerebral arteries

The time course of contractile responses to alpha-adrenoceptor agonists was investigated using various arteries isolated from dogs and monkeys. The contractile response to norepinephrine was increased during the time course of the experiment in canine basilar and internal carotid arteries, whereas the response of isolated canine external carotid arteries and monkey internal carotid arteries did not change significantly. Treatment with 10(-7) M propranolol, 5 x 10(-6) M cocaine plus 10(-5) M hydrocortisone, or 5 x 10(-5) M acetylsalicylic acid did not significantly affect the time-dependent potentiation of the norepinephrine-induced contraction in canine internal carotid arteries. The time-dependent enhancement in the response to norepinephrine was also observed in the arterial preparations from which the endothelial cells were removed. The contractile response of canine internal carotid arteries to phenylephrine did not alter significantly throughout the experiments. On the other hand, the responses to clonidine and xylazine were markedly enhanced with time. Significant potentiation of the norepinephrine-induced contraction was observed in canine internal carotid arteries treated with 10(-8) M prazosin, whereas 10(-8) M yohimbine attenuated the time-dependent potentiation. These results suggest that the contractile responses of isolated canine basilar and internal carotid arteries to norepinephrine are potentiated during the course of the experiment, which is likely to be related, in part, to an enhancement in alpha 2-adrenoceptor mediated contraction.

Preparative high-yield electroelution of proteins after separation by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and its application to analysis of amino acid sequences and to raise antibodies

A method for the preparative high-yield electroelution of proteins from sodium dodecyl sulphate (SDS) polyacrylamide gel strips was established. The method consisted of SDS-polyacrylamide gel electrophoresis, detection of proteins with sodium acetate and electrophoretic elution at 200 V for 3 h by utilizing a horizontal flat-bed gel electrophoresis apparatus. Standard proteins with molecular masses of 14-66 kilodalton (cytochrome c, aldolase, ovalbumin and bovine serum albumin) were recovered with an average yield of 73.6 +/- 2.3%. A membrane-bound protein, rat skeletal muscle Ca(2+)-ATPase (100 kilodalton) was also well recovered (over 60%). This method was applicable to the purification of proteins required for N-terminal amino acid sequencing and to raise antibodies.

Beta-1 and beta-2 adrenoceptors mediate smooth muscle relaxation in bovine isolated mesenteric lymphatics

The relaxant effects of beta adrenoceptor agonists were investigated in isolated bovine mesenteric lymphatics which had been contracted by 5-hydroxytryptamine. Addition of isoproterenol (a nonselective beta agonist), denopamine (a selective beta-1 agonist) and procaterol (a selective beta-2 agonist) caused concentration-dependent relaxations in the lymphatic preparations. There was no significant difference in the relaxant responses to the beta adrenoceptor agonists between the preparations with and without endothelium. Treatment with 10(-7) to 3 x 10(-6) M metoprolol (a selective beta-1 antagonist) shifted the concentration-response curve for denopamine to the right, whereas 10(-9) to 3 x 10(-8) M ICI 118,551 (a selective beta-2 antagonist) did not affect the relaxant response to denopamine. The relaxations of bovine mesenteric lymphatics induced by isoproterenol were suppressed by both metoprolol and ICI 118,551. The procaterol-induced relaxations were inhibited by 10(-9) to 3 x 10(-8) M ICI 118,551 but not by 10(-7) to 3 x 10(-6) M metoprolol. Schild plot analyses showed that the slope and pA2 values for metoprolol against denopamine were 1.10 and 7.59, respectively, and that those for ICI 118,551 against procaterol were 0.91 and 9.96. These results suggest that both beta-1 and beta-2 adrenoceptors are located on the smooth muscle cells in bovine mesenteric lymphatics and that stimulation of either receptor produces a marked relaxation.