Chronopharmacology of enalapril in hypertensive patients

The pharmacokinetics and pharmacodynamics of enalapril, an angiotensin converting enzyme inhibitor, are reported to vary with the time of administration. The present study was undertaken to examine whether the effect of enalapril on plasma bradykinin (BK), substance P and prostaglandin E2 (PGE2), which are likely to be involved in the mechanism of enalapril-induced cough, might also be affected by its time of administration. Enalapril 5 mg or placebo was given orally at 10:00 h (day trial) or 22:00 h (night trial) to 12 patients with essential hypertension. Serum concentrations of total drug (enalapril + enalaprilat, its active metabolite) during the day and night trials did not differ significantly at any time. However, serum enalaprilat tended to be higher and its maximum concentration greater in the day trial than in the night trial. Blood pressure 24 h after administration of enalapril was reduced at 22:00 h, but not at 10:00 h. Plasma BK tended to increase following enalapril administration at 10:00 h, but not at 22:00 h. Remarkable increases in plasma BK were observed in two patients in the day trial and one of them also complained of cough. However, no such increase in plasma BK or subsequent adverse effect were recorded in the night trial. Plasma substance P and PGE2 did not change significantly following enalapril administration either in the day or night trial. The results suggest that the response of BK to enalapril is affected by the time of administration. In patients who complain of cough during treatment with enalapril during the daytime, this adverse effect might be diminished or eliminated by a switch to night-time administration.

The development of interneurons in the chick embryo spinal cord following in vivo treatment with retinoic acid

To investigate the role of retinoic acid (RA) in the development of interneurons in the spinal cord, we examined the expression of cellular retinoic acid binding protein type I (CRABP I). The earliest developing interneurons in the chick spinal cord can be divided into two major groups: circumferential (C) neurons and primitive longitudinal (PL) neurons. In brachial segments, both types of interneurons began to express CRABP I at stage (st.) 13+ of the V. Hamburger and H.L. Hamilton (1951, J. Morphol. 88:49-92) stage series, which is before the onset of axonogenesis. Subsequently, with the onset of axonal outgrowth, C neurons and PL neurons expressed CRABP I in their cell bodies, axons, and growth cones. The expression of CRABP I was developmentally regulated. CRABP I immunoreactivity gradually decreased after st. 36 (embryonic day [E] 10) such that no interneurons expressed this protein by E21. The transient expression of CRABP I during a period of intensive axonal growth suggested that RA may be involved in the development of interneurons. To test this idea, we implanted an all-trans RA-containing ion exchange bead into either rostral segments of the spinal cord at st. 12-13 or into caudal segments at st. 15-16, all stages that are well before the appearance of CRABP-I-positive neurons in these segments. In the RA-treated spinal cord, increased numbers of pyknotic cells were found predominantly in dorsal regions, presumably reflecting the death of neuroepithelial cells, C neurons and premigratory neural crest cells. Surviving C neurons in the RA-treated spinal cord extended their axons ventrally toward the floor plate as in control embryos. PL neurons also projected their axons rostrally or caudally in the RA-treated spinal cord, similarly to control embryos. However, the proportion of caudally projecting PL neurons was significantly increased in segments rostral to the RA-containing bead. These results suggest that RA may regulate the survival and axonal orientation (directionality) of subpopulations of spinal interneurons.

Platelet-activating factor-induced loss of vascular responsiveness to noradrenaline in pithed rats: involvement of nitric oxide

The role of nitric oxide and cyclo-oxygenase products in the platelet-activating factor (PAF)-induced hyporesponsiveness to noradrenaline was investigated in pithed rats. Infusion of PAF (30 ng/kg/min) for 60 min reduced the mean arterial blood pressure and impaired the pressor responses to noradrenaline (10 ng/kg, 100 ng/kg, 1 microgram/kg). Administration of NG-monomethyl-L-arginine (L-NMMA, 30 mg/kg) restored the reduced MABP and the impaired responses to their original levels. Indomethacin (5 mg/kg) had no significant effect on the PAF-induced hyporesponsiveness. Administration of 30 mg/kg L-NMMA caused hypertension in the PAF vehicle-treated animals and reduced the pressor response to 1 microgram/kg noradrenaline. Administration of 3 mg/kg L-NMMA had no significant effect on the responsiveness to noradrenaline. These results suggest that nitric oxide contributes to the PAF-induced hyporesponsiveness to noradrenaline and that cyclo-oxygenase products do not play a major role in this hyporesponsiveness.

Increase in plasma nitric oxide end products following rat cortical injury

The changes in plasma nitric oxide (NO) end products, nitrite (NO2-) and nitrate (NO3-), were studied following cortical injury in rats. At 3 days after stereotactic cortical injury (day 3), plasma NO end products were significantly increased (P < 0.01), and decreased by day 7. This increase on day 3 was inhibited by a selective inhibitor of inducible NO synthase (NOS), aminoguanidine (100 mg/kg, i.p. on days 1 and 2, P < 0.001). The present study first demonstrated the temporary increase in plasma NO end products, which is attributable to the inducible NOS activation after cerebral injury.

Expressing kidney uptake during 99Tcm-MAG3 renography in terms of administered activity

In a study of gamma-camera renography, a digitized time-activity curve, or renogram, was standardized in terms of absolute renal uptake. The algorithm for standardization of the renogram was based on a gamma-camera uptake method employed by Gates and Schlegel et al. All count rates for the background-corrected renograms were converted to percent renal uptake per injected dose per minute (%RU). The maximum value for the scale on the y-axis was set at 20% RU. The renograms were generated from 66 kidneys in 35 patients (27 males, 8 females) aged 19-80 years. Using the newly developed computer program, the shape of the renograms was considered abnormal between 8/52 (15%) and 10/53 (19%) kidneys, depending on the observer, all of which were classified as normal when displayed conventionally. All the renograms for 4 patients with one poorly functioning kidney, and between 8 (28%) and 10 (32%) renograms for 31 patients with two poorly performing kidneys, exceeded the maximum g-axis value of 20% RU. Expression of the renograms based on absolute uptake is helpful in avoiding the potential problem of two poorly functioning kidneys, which may be considered near-normal in terms of count rate. The maximum value on the y-axis in 99Tcm-MAG3 renography should be fixed between 25 and 30% RU, while the actual amplitude of the standardized renogram may depend on the method used for quantification.

Ethanol induces heterogeneous reduction of cytochrome aa3 within perfused rat liver lobule assessed using microspectroscopy

The redox state of cytochrome aa3 was measured at microspots (20 microns diameter) within the lobule of perfused rat livers, using reflectance microspectroscopy, and the effect of ethanol infusion on sublobular distribution of the redox states was evaluated. A sigmoidal relationship was observed between oxygen delivery and the reduction of cytochrome aa3 in both the periportal and pericentral regions of the liver lobule when the influent O2 concentration was decreased in a graduated manner. This sigmoidal curve was shifted to the more reduced state by ethanol infusion, with ethanol (25-100 mM) increasing the degree of cytochrome aa3 reduction in a dose-dependent manner according to the distance from the periportal region along a sinusoid. This increase was spatially heterogeneous within a liver lobule. These data indicate that ethanol accelerates cytochrome aa3 reduction, with a distinct gradient of reduction along sinusoids but a heterogeneous distribution within the liver lobule.

[High dose epidural fentanyl suppresses the increase in cortisol levels during open chest surgery]

We investigated the effect of high dose epidural fentanyl (HEF) on plasma levels of epinephrine (E), norepinephrine (NE) and cortisol (C) during open chest surgery (OCS). Twenty five patients undergoing open chest surgery was divided randomly into two groups. Thirteen patients had HEF (F-Group) and the rest of 12 patients had epidural mepivacaine (M-Group). Epidural puncture (Th5-6) and catheterization were performed before anesthetic induction. Anesthesia was induced with thiamylal (5 mg.kg-1) and trachea was intubated after injection of vecuronium (0.1 mg.kg-1). Anesthesia was maintained with 50% N2O and isoflurane as needed. After 0.2 ml.kg-1 of fentanyl was injected through the epidural catheter, fentanyl was infused continuously (0.05 mg.h-1) in F-Group. In M-Group, after 0.2 ml.kg-1 of 1% mepivacaine was injected through the epidural catheter, 1% mepivacaine was infused continuously (10 ml.h-1). For the measurement of E, NE and C, blood samples were collected at following points; 1) before anesthetic induction, 2) before incision, 3) during open chest and 4) in the recovery room. In both groups, E and NE levels did not change significantly. In F-Group, plasma C levels decreased significantly when chest was opened. C levels in F-Group, were significantly lower than in M-Group before incision and during open chest.

Effects of NG-nitro-L-arginine and/or L-arginine on experimental pulmonary metastasis in mice

Effects of NG-nitro-L-arginine methyl ester (L-NAME; an inhibitor of nitric oxide (NO) synthase) and/or L-arginine (substrate of NO synthase) on pulmonary metastasis of murine melanoma and Lewis lung carcinoma cells were investigated. L-NAME, L-arginine or both L-NAME and L-arginine was injected i.p. into mice 5, 3, and 1 h before and 1, 3, 5, and 7 h after the injection of tumor cells into mice via a tail vein. The administration of L-NAME (9.3 mumol/mouse) alone or L-arginine alone (46.5 or 186 mumol/mouse) potentiated pulmonary metastasis of highly and poorly metastatic B16 melanoma cells. L-NAME alone also increased the number of pulmonary metastasis of Lewis lung carcinoma cells, but L-arginine (185 mumol/mouse) did not. However, the combination of L-NAME and L-arginine increased the number of pulmonary metastasis of both the melanoma and Lewis lung carcinoma cells synergistically. L-NAME or L-arginine administration enhanced the retention of B16 melanoma cells in the lungs examined 24 h after the tumor cell injection. Synergistic effect of L-NAME and L-arginine was also seen in the tumor cell retention. The present results suggest that the metastatic potentials of the tumor cells do not simply correlate to NO production in vivo.

Biochemical characterization and immunolocalization of SC2 protein: SC2 protein is indistinguishable from the cell adhesion molecule axonin-1

SC2 is a monoclonal antibody that was previously shown to recognize a subset of neurons in the developing nervous system of the chick. We have now used the SC2 monoclonal antibody to purify from chick embryo brain membranes a glycoprotein that migrates at approximately 125 kDa on SDS/PAGE. The size of this protein and its distribution pattern in the spinal cord are similar to that observed for axonin-1. A polyclonal anti-axonin-1 antibody R26 specifically reacted with the SC2 protein from brain. This antibody, as well as polyclonal antibody (369) against purified SC2 protein, reacted with 115-130 kDa proteins in vitreous humor, a rich source of axonin-1, and with similar sized proteins precipitated from vitreous humor by the 369, and SC2 antibodies. Treatment of SC2 protein isolated from chick brain membranes with PI-PLC indicated that it contains a glycophosphatidylinositol (GPI) moiety. Co-aggregation experiments using Covaspheres with covalently bound proteins indicated that SC2 protein binds heterophilically to Ng-CAM. Immunohistochemical analysis of chick embryos showed that SC2 protein is abundant in the sensory nerve bundles of both the central and peripheral nervous systems during development. Its expression was restricted and it was specifically localized in the dorsal funiculus of the spinal cord, as well as in olfactory, retinal, trigeminal, vestibulocochlear, glossopharyngeal and vagal nerve fibers. The biochemical and immunohistochemical data show that SC2 protein is axonin-1, and the immunolocalization studies support the hypothesis that SC2 protein may play a role during development of particular fiber systems by interacting with other cell adhesion molecules such as Ng-CAM.

Direct proof of nitric oxide formation from a nitrovasodilator metabolised by erythrocytes

When 15N-isosorbide dinitrate was injected into rats, the venous blood showed a 2-line hyperfine structure in the electron spin resonance (ESR) spectra of NO hemoglobin (HbNO), proving generation of 15N-NO. When human blood was mixed with 15N-isosorbide dinitrate anaerobically, ESR spectra showed initially 14N-HbNO, which was then overwhelmed with the increased 15N-HbNO. With deoxygenation of the blood of another 4 male donors without addition of isosorbide dinitrate, two showed 14N-HbNO, but others did not, suggesting varied amount of NO-precursers, nitrosothiols, in human blood. Neither N-ethylmaleimide nor S-hexylglutathione, a glutathione-S-transferase inhibitor, inhibited the formation of UbNO in the hemolysate mixed anaerobically with isosorbide dinitrite.

[Treatment of prostatic carcinoma with UFT and leucovorin--basic study using SRCA]

Combination effect of UFT and leucovorin against the rat prostatic carcinoma (R-3327) was evaluated by the subrenal capsular assay (SRCA) using nude mice. Anticancer effect of UFT was augmented by co-administration of both low and high dose leucovorin. These results suggest a clinical usefulness of UFT administration with leucovorin for the patients with hormonally refractory advanced prostatic carcinoma.

[An evaluation of the hemodynamics in metastatic liver tumor by using ultrasound color Doppler flow mapping examination]

Eighty-one patients with metastatic liver tumors were studied by ultrasound color Doppler flow mapping examination. Primary origins consisted of gastric (19 cases), colorectal (40 cases), breast (7 cases), pancreatic (3 cases), gallbladder (3 cases) cancers and the others (9 cases). Metastatic lesions originated from breast, gastric and colorectal cancers had higher detection rates, however no blood flow could be observed within metastatic liver cancers from pancreatic and gallbladder cancers. There were no differences among the maximum blood flow velocity (Vmax), the resistance index (RI) and the pulsatile index (PI) in various metastatic liver tumors. In case of colorectal cancers, metastatic lesions originated from moderately differentiated adenocarcinoma had significantly lower RI (p < 0.05) and PI (p < 0.01) than that from well differentiated adenocarcinoma. In conclusion, ultrasound color Doppler flow mapping examination is a useful method for evaluation of the blood flow within metastatic liver tumors and could offer the histological differentiation of the primary origins, in case of metastatic liver cancers originated from colorectal cancers.

Assessment of rate of O2 release from single hepatic sinusoids of rats

Characteristics of O2 release from single hepatic sinusoids are described in relation to the sinusoidal O2 inflow for the first time. Microspectroscopic measurement of the rate of O2 release (RO2) from single sinusoids to surrounding hepatocytes was carried out at the edge of the liver of anesthetized rats. The oxyhemoglobin inflow ([HbO2] inflow) into sinusoids, which is a product of sinusoidal blood flow rate and inflowing oxyhemoglobin concentration ([HbO2]), was varied by exchange transfusion of blood with physiological saline. 1) RO2 from single hepatic sinusoids of control rats was fairly constant [0.66 +/- 0.14 (SD) nmol.cm-2.s-1, with 18 sinusoids of 9 rats] over a wide range of [HbO2] inflow (50-200 fmol/s). 2) In the cases of mild anemia, [HbO2] inflow scarcely decreased but RO2 increased, probably because of the increased metabolism of hepatocytes. 3) In the cases of severe anemia, [HbO2] inflow decreased below 50 fmol/s and RO2 decreased accordingly. 4) In all cases no difference was observed between the RO2 values obtained from periportal zone and those from pericentral zone. These results are discussed on the bases of the vascular structure and function of hepatic sinusoids and on the animal model of hemorrhagic shock.

Electron spin resonance signals of non-heme iron as an indicator of ischemia-reperfusion injury of the liver

Although many different methods have been proposed to assess the viability of preserved or reperfused liver, none of them are definitive. In this study, we investigated the usefulness of electron spin resonance (ESR) spectrometry in the rat liver ischemia model. Ischemia was induced in Wistar rats weighing 250-300 g by clamping the portal triad. At 15, 30, 60, or 90 min after the clamping, the liver was reperfused by removing the clamp. Liver specimens obtained before and after the clamping and also 30 min after reperfusion were frozen with liquid nitrogen and analyzed at 140K by ESR spectrometry. Two significant signals of g-values of 2.0 and 1.96 were observed with the fresh liver. The former was thought to be a mixture of CoQ, flavin, and succinate radicals. The intensity of this signal did not change throughout the experimental period. The latter was regarded as the signal from non-heme irons of mitochondria. The intensity of this signal decreased as the ischemic time became longer (the ratio to the signal intensity of the fresh liver was 0.69 +/- 0.19, 0.22 +/- 0.08, 0.20 +/- 0.05, and 0.18 +/- 0.09 at the end of 15, 30, 60, and 90 min of ischemia, respectively). After reperfusion, each ratio recovered to 0.95 +/- 0.12, 0.77 +/- 0.06, 0.56 +/- 0.15, and 0.37 +/- 0.20, respectively. This suggests that detectable signals with Fe(II)-Fe(III) decreased and became undetectable as the reduced form of non-heme irons under the anoxic state. Then, after reperfusion, the reduced form of non-heme irons decreased and the oxidized form increased. Incomplete recovery was thought to be due to decrease in the viability or function of liver cells. ATP and energy charge had the same tendency as the non-heme iron signal observed with ESR. There was a significant correlation between the non-heme iron signal and energy charge (y = 0.73x + 0.32, r = 0.78, P < 0.001), demonstrating that the signal intensity reflects the viability or function of liver cells. This study suggests that the signal from non-heme irons detected by ESR can be a good parameter of the metabolic state of the liver in ischemia and reperfusion. This method is simple and quick and should be applicable in clinical liver transplantation.

Nitrosyl hemoglobin production during reperfusion after focal cerebral ischemia in rats

We first detected a definite nitrosyl hemoglobin (HbNO) signal in the jugular blood by electron spin resonance spectroscopy during early reperfusion after cerebral ischemia. A distinct three-line hyperfine structure, characteristic to HbNO, was demonstrated at 30 min of recirculation after 2 h of middle cerebral artery occlusion in rats. Only a weak HbNO signal was observed in animals with 2 h sustained ischemia or with sham operation. The present findings suggest that reperfusion after cerebral ischemia facilitates nitric oxide generation in the brain, which leads to the increased nitrosylation of erythrocyte hemoglobin in the cerebral circulating blood.

Microspectroscopic measurement of the optical properties of rat liver in the visible region

Microspectroscopy is used to investigate optical properties of haemoglobin-free perfused rat liver. Visible spectra of 20 microns diameter spot size were measured in transmission and/or reflection modes as a function of the thickness (< 1200 microns) of the liver-edge. Optical density (OD) in transmission mode increased with the increasing liver thickness, whereas in reflection mode OD decreased but became almost constant above a certain thickness (c.600 microns) of the liver. The Kubelka-Munk (KM) two-flux model, with a minor modification, was applied successfully to the analysis of the changes in OD as a function of the thickness. This approach estimates the KM absorption coefficient (EKM), KM scattering coefficient (SKM) and effective penetration depth (delta eff) of the liver. The optical properties were similar to reported values, obtained with different methods.

Administration time-dependent change in the effect of spironolactone in rats

The present study was undertaken to examine whether the natriuretic effect of spironolactone, a competitive antagonist of mineralocorticoid, varies with its time of administration. Wistar rat maintained under the condition of light from 7 hr to 19 hr were divided into two groups. The first group had a bilateral adrenalectomy and received a 50-mg deoxycorticosterone acetate (DOCA) tablet intraperitoneally (DOCA group). The second group had a sham operation (control group). Spironolactone (50 mg/kg) was given orally at 12 hr or 24 hr, and the 8-hr urine was collected. At the end of the experiment, the blood sample for measurement of aldosterone was obtained at 12 hr and 24 hr in the control group. The natriuretic effect of spironolactone in the 24 hr-trial was significantly greater than that of the 12 hr-trial in the control group. However, such a time-dependent difference was diminished and did not reach statistical significance in the DOCA group. The plasma aldosterone concentration at 24 hr was significantly higher than that at 12 hr in the control group. These results suggest that the natriuretic effect of spironolactone varies with its time of administration. Daily variation in mineralocorticoid activity might be involved in this chronopharmacological phenomenon of spironolactone.

ESR spectral transition by arteriovenous cycle in nitric oxide hemoglobin of cytokine-treated rats

Nitric oxide (NO) generation was induced in rats by Escherichia coli lipopolysaccharide (LPS) as detected by electron spin resonance (ESR) signals of NO hemoglobin (HbNO). However, there were inconsistencies in ESR spectral shape among them. We have therefore carried out a systematic study to clarify the in vivo spectral changes. First, the spectra of the alpha-NO heme species had the distinct three-line hyperfine structure in venous blood but not in arterial blood in all rats treated with tumor necrosis factor, interleukin-1, and/or LPS, and methemoglobin was not detected at the g = 6 (high-spin methemoglobin) region. Second, when the treated rats died, the three-line hyperfine structure was very distinct even in arterial blood. Third, even if HbNO was formed by injection of nitrite to rats, the three-line hyperfine structure of HbNO in venous blood was more marked than that in arterial blood, independent of the appearance of the methemoglobin signal. Fourth, an ex vivo study using whole blood demonstrated that the three-line hyperfine structure intensified lineally when O2 saturation of hemoglobin decreased but disappeared on reoxygenation of hemoglobin. These results directly demonstrate in vivo quaternary structural transition of the hemoglobin tetramer from the high-affinity state in the arterial cycle to the low-affinity state in the venous cycle. The transition makes the diverse ESR spectra of HbNO in vivo.

Elevation of plasma nitric oxide end products during focal cerebral ischemia and reperfusion in the rat

We investigated the alterations in the stable end products of nitric oxide, i.e., nitrate and nitrite, in the plasma during and after rat focal cerebral ischemia by an automated procedure based on the Griess reaction. At 2 h of middle cerebral artery (MCA) occlusion, plasma nitrate/nitrite levels were significantly higher (53 +/- 8 microM, mean +/- SD, n = 5, p < 0.05) than in rats with sham operation (36 +/- 9 microM, n = 5), and were mildly elevated at 4 h of MCA occlusion (42 +/- 9 microM, n = 5, n.s.). At 30 min of reperfusion after 2 h of MCA occlusion, plasma nitrate/nitrite levels were more markedly elevated (72 +/- 7 microM, n = 5, p < 0.01 vs. sham operation), but were moderately elevated at 2 h of reperfusion after 2 h of MCA occlusion (61 +/- 10 microM, n = 5, p < 0.05). Plasma nitrite levels were not changed during these experimental periods. Administration of 20 mg/kg of NG-nitro-L-arginine methyl ester (L-NAME) significantly decreased plasma nitrate/nitrite as well as nitrite at 30 min of reperfusion after 2 h of MCA occlusion (n = 5), but 2 mg/kg of L-NAME did not (n = 3). The effect of 20 mg/kg of L-NAME on plasma nitric oxide end products was reversed by the simultaneous administration of 200 mg/kg of L-arginine (n = 3), but not D-arginine (n = 3). The present study suggests that the L-arginine-nitric oxide pathway is activated during acute cerebral ischemia and reperfusion.