A comparative study of the respiratory responses to bronchoactive agents in rhesus and cynomolgus monkeys

Respiratory responses to a variety of known bronchoactive agents were compared in anesthetized rhesus (Macaca mulatta) and cynomolgus (Macaca fascicularis) monkeys. Administration of 0.1 to 1.0% histamine aerosols resulted in an increase in airway resistance of 50 to 200% and a decrease in lung compliance of 30 to 80%. Aerosols of prostaglandin E2 (1 mg/ml), terbutaline (10 mg/ml), and isoproterenol (10 mg/ml) or iv aminophylline (up to 7.0 mg/kg) administered concomitantly with histamine produced a transient reversal of the histamine-induced changes in both species. Since the rhesus and cynomolgus monkeys responded in a comparable manner to these bronchodilator agents, the cynomolgus monkey appears to be an additional valuable model for the evaluation of potential bronchoactive compounds.

Respiratory responses to Ascaris antigen in rhesus and cynomolgus monkeys

Responses to Ascaris antigen were evaluated in rhesus and cynomolgus monkeys. Of 19 cynomolgus monkeys tested, 15 were found to have cutaneous reactivity to Ascaris: 13 of these responded to Ascaris aerosols with changes in respiratory function including an increase in respiration rate, decrease in tidal volume and peak expiratory flow rate, decrease in dynamic compliance, and an increase in resistance. Four of the six rhesus monkeys studied with cutaneous reactivity to Ascaris responded to Ascaris aerosols: the changes in respiratory function observed after the Ascaris challenge in these monkeys were similar to those observed in the cynomolgus monkeys. Responses to repetitive Ascaris challenges were obtained in monkeys of both species with a recovery period of 30 to 60 min between challenges. In monkeys of both species that reacted to Ascaris aerosols, blood pressure was elevated transiently; changes in heart rate were variable. Changes in cardiovascular measurements were not observed in monkeys that did not respond to Ascaris aerosols. Thus, it appears that the cynomolgus monkey responds to an aerosol Ascaris challenge in a manner similar to the rhesus monkey and is an additional suitable model for the study of allergic respiratory responses.

Evaluation of rotenone and related compounds as antagonists of slow-reacting substance of anaphylaxis

Rotenone (1), dihydrorotenone (2), isorotenone (3), mutarotenone (4), and deguelin (12) were found to be potent antagonists of slow-reacting substance of anaphylaxis (SRS-A) in vitro. However, these compounds were also shown to inhibit histamine, serotonin, and acetylcholine at only ten times their IC50 concentrations for SRS-A antagonism. Rotenone (1) and several related compounds were also evaluated in an in vivo guinea pig anaphylaxis model. Several of these compounds and FPL 55712 (I) were effective in prolonging collapse times of animals which received an aerosol challenge of an antigen to which they had been sensitized.

Delta-9-tetrahydrocannabinol on isolated human bronchioles

Experiments were conducted to investigate the bronchodilating action of delta-9-tetrahydrocannabinol (THC) using normal human lung tissue obtained post mortem. Isolated rings of human bronchioles contracted to histamine, carbachol, and prostaglandin F(2a)(PGF(2a)) and relaxed to isoproterenol. THC (5 X 10(-4)M) did not alter the responses of the bronchial rings to histamine, whereas methapyrilene (10(-6)M) antagonized these responses. Atropine (2 X 10(-6)M) had a highly significant effect on the responses of the bronchioles to carbachol: there was also a significant effect of THC (5 X 10(-4)M), but to a much lesser extent than atropine. Propranolol (10(-6)M) pretreatment significantly antagonized the relaxant responses of the bronchioles to isoproternol: THC antagonized these responses to a smaller degree. Incubation with THC did not cause relaxation of resting tissues or tissues in which a spasm had been induced. These data suggest that THC does not have significant direct effects in human bronchial smooth muscle and that bronchoactivity observed in vivo is likely to be of a nondirect or central origin.

Effects of hypertonic mannitol on contractile responses and 45Ca movements in isolated canine arteries

The effects of hyperosmotic mannitol on vascular smooth muscle contractile responses and on 45Ca movements were examined in different isolated canine arteries. Prior exposure to 50 mM mannitol decreased contractile responses elicited with dopamine (DA) in helical strips of canine terminal mesenteric arteries (Tm) and decreased the contractile response elicited with potassium (K+) in both isolated left anterior descending (LAD) and circumflex coronary arteries. Tension responses induced by norepinephrine or DA in the Tm and K+ and prostaglandin F2 alpha in LAD were relaxed by subsequent exposure to mannitol. Mannitol increased the uptake of 45Ca in Tm arteries. Exposure of the Tm and branches of the LAD to mannitol during the washout of 45Ca resulted in a decrease in the rate of loss of 45Ca; the presence of either K+, Mg2+, or ethylenediamine tetraacetic acid during the washout did not prevent the observed mannitol-induced decrease in 45Ca efflux. These effects of mannitol on 45Ca efflux without a concomitant major change in net 45Ca uptake could be attributed to an increase in bound Ca2+ at relevant membrane sites or stores. Thus, hypertonic mannitol may alter contractile responsiveness of selected canine arteries by impeding the release of bound and/or sequestered Ca2+ and, in this manner, decreasing the Ca2+ concentration at the contractile elements.

Calcium incorporation by canine aortic smooth muscle microsomes

The accumulation of calcium (Ca2+) and factors influencing Ca2+ incorporation in vascular smooth muscle were examined in a microsomal fraction prepared from canine aortae. The accumulation of Ca2+ required the presence of ATP and increased over time. Furthermore, the incorporation of 45Ca into the microsomal preparation was stimulated both in the presence of oxalate and when the Ca2+ concentration of the bathing media was elevated from 20 micron to 40 micron. Calcium uptake (with oxalate) was temperature-dependent; uptake was unaffected by azide. Both lanthanum (La3+) and phosphatidyl serine (PS) inhibited ATP-dependent uptake in a concentration-dependent manner. In the presence of ATP, calcium binding (without oxalate) was slightly inhibited by La3+, whereas PS had no effect under these conditions. When ATP was removed from the incubation medium, the presence of PS stimulated both the uptake and binding of 45Ca, whereas La3+ decreased both uptake and binding. These findings support the idea that La3+ binds on the surface of the vesicles and, in this manner, decreases available Ca2+ sites, whereas PS appears to increase the number of Ca2+ sites by either entering the membranes or adsorbing on it.

Characteristics of 45Ca uptake and efflux in rat lung slices

The distribution and movements of 45Ca were investigated in lung slice preparations obtained from rats. The accumulation of 45Ca was measured in either 5.0 mM Ca2+, 0.5 mM Ca2+ or 0-Ca solutions. The 45Ca tissue to medium ratio was greatest in the 0-Ca solution; the presence of either 5.0 mM Ca2+ or 0.5 mM Ca2+ reduced this ratio 8- and 5-fold, respectively. Efflux of 45Ca indicated that there are at least two washout components. Exposure to either La3+ or Sr2+ (0.5 mM) during the washout resulted in a transient increase in 45Ca efflux (Sr2+ greater than La3+), whereas 0 degrees C slowed the loss of 45Ca. Uptake of 45Ca was increased by the metabolic inhibitor iodoacetic acid and inhibited in the presence of either La3+ or Sr2+. These findings indicate that the 45Ca accumulated within the lung is not readily depleted and a portion appears to accumulate at intracellular or less superficial sites or stores.

Effect of pulmonary edema on drug transport and binding in rat lung

The pulmonary absorption and uptake of (35S)phenol red ((35S)PR was measured in anesthetized rats with alpha-naphthylthiourea- (ANTU) induced lung edema. When (35S)PR solution was injected through a tracheal cannula in control animals and the percentage of the tracheal cannula in control animals and the percentage of the dose unabsorbed plotted semilogarithmically against time, an apparent first-order absorption rate was obtained. In contrast, in rats with ANTU-induced edema, the absorption time curve showed at least two different first-order components. Increasing the concentration of (35S)PR from 0.01 to 3 mM resulted in a decrease in the percentage absorption of the compound in controls compared with a relatively constant percentage absorption in edematous lungs. (35S)PR uptake by lung slices from ANTU-treated rats was decreased in the presence of IAA and a N2 atmosphere, and the dye accumulated at a faster rate and to a greater extent than in controls. The results suggest that although energy-dependent drug transport mechanisms remain intact, the porosity of the absorbing membranes and the extent of drug binding in the lung are increased markedly in the presence of edema.

Contractile function and 45Ca movements in vascular smooth muscle of nonhuman primates: effects of aminoglycoside antibiotics

1. The effects of 7mM neomycin, 10 mM kanamycin and 5 mM gentamicin on vascular smooth muscle contractile responses and 45Ca movements were examined in arterial preparations isolated from nonhuman primates (squirrel monkeys, capuchin monkeys and baboons). 2. Present findings demonstrate that these antibiotics inhibit contractile responses and alter 45Ca movements in monkey blood vessels, and suggest that the manner in which these agents affect vascular smooth muscle from nonhuman primates does not differ qualitatively from their effects in canine and rabbit vascular preparations.

Distribution of a lanthanide (147 Pm) in vascular smooth muscle

In order to ascertain whether trivalent rare earth ions such as lanthanum (La+++) penetrate the cell membrane under physiological conditions, the extracellular and cellular distribution of promethium (147 Pm), a carrier-free rare earth radioisotope, was examined in rabbit aortic smooth muscle. As the duration of incubation was lengthened, uptake of 147Pm continued to increase; it was inhibited by La+++ and other rare earth ions (Nd+++, Lu+++) only when the 147 Pm/rare earth concentration ratio exceeded 1:10(6). However, equally high concentrations of Ca++ had no effect on 147Pm uptake. Efflux of 147Pm was only transiently increased by 1.5 mM La+++, and exposure to 0.05 mM EDTA elicited an increased 147Pm efflux with both transient and maintained components. The magnitude of the EDTA-induced increase in 147 Pm efflux was similar over a 30-fold range of EDTA concentration (0.05-1.5 mM); the limiting factor for 147Pm efflux is the rate of 147Pm desorption from the tissue rather than the extracellular concentration of EDTA. Loss of 147Pm in the presence of 0.05 mM EDTA could be described in terms of two specific washout components (the more rapid of which included 147Pm within the extracellular space and the slower of which had half-times of washout of approximately 7-10 minutes). Uptake of 147Pm was inhibited by lowering the incubation solution temperature to 0 degrees C or by procaine. However, concentrations of metabolic inhibitors (iodoacetate and dinitrophenol) which diminish loss of Ca++ from the cell did not decrease either the uptake or efflux of 147Pm. Thus, significant quantities of 147Pm do not appear to be accumulated within the cell or transported out of the cell; distribution of 147Pm can be most simply described in terms of a binding at and desorption from surface acessible fiber sites.

Comparison of uptake and binding of disodium cromoglycate and phenol red in rat lung

In rat lung slices 3H-disodium cromoglycate (3H-DSCG) (0.001 mM) was taken up rapidly and 3H-DSCG tissue spaces, which equilibrated by 30 minutes, remained constant over a 4-hour incubation period. In contrast, 35S-phenol red (0.001 mM) accumulated in lung slices to a much greater extent than did DSCG, and the measured tissue spaces continued to increase over a 3-hour incubation period. In the presence of either phenol red (1 mM) or the metabolic inhibitors, iodoacetic acid (10(-4) M) and dinitrophenol (10(-4) M), 3H-DSCG uptake was significantly decreased. Accumulation of 3H-DSCG in lung slices and binding to tissue homogenates (pH 7.4) was also decreased when Ca and Mg ions were omitted from the bathing solution. Although DSCG and phenol red mutually inhibited the accumulation of one another over time in lung slices and 3H-DSCG (0.001 mM) binding to lung homogenates was decreased in the presence of 1 mM phenol red, 35S-phenol red efflux was not altered by the addition of 1 mM DSCG during the washout. Thus, it appears that, in rat lung, DSCG and phenol red share a common binding site(s) for uptake, possible on the transport "carrier." Also, there appear to be additional pulmonary binding sites for phenol red. These sites are not occupied by DSCG and their presence could account for the differences observed in the extent of accumulation of the two compounds in lung slices.

Alteration by phosphatidyl serine of tension responses and 45Ca distribution in aortic smooth muscle

The effects of phosphatidyl serine (PS) on 45Ca distribution, 45Ca movements and contractions were examined in rabbit aortic smooth muscle. Contractile responses to submaximal concentrations of norepinephrine and histamine were potentiated by prior exposure to PS, but equivalent responses to potassium were unaffected. Addition of PS to the incubation solution decreased 45Ca uptake; exposure of aortic strips to PS during washout of either 45Ca or promethium (147Pm) resulted in maintained increases in efflux. These PS-induced alterations in net loss of 45Ca or 147Pm can be attributed to a decreased membrane reuptake and/or rebinding. However, the presence of PS during the washout significantly reduced the increases in 45Ca efflux rate elicited with either 0.05 mM concentrations of Ca++ or ethylenediamine tetraacetic acid. Thus, in rabbit aortic smooth muscle, exogenous PS can alter the availability and/or exchangeability of a membrane-bound Ca++ fraction. By specifically increasing the affinity for Ca++ at relevant membrane sites or stores. PS may enhance the ability of vascular smooth muscle to respond to stimulatory agents that mobilize Ca++ from these sites and, in this manner, potentiate contractile responses.

Effects of metiamide on distribution of 14C-histamine in aortic smooth muscle

The effects of metiamide on 14C-histamine movements and on contractions induced by histamine were studied in rabbit aortic smooth muscle. Low temperature (0 degrees C) and pretreatment with aminoguanidine or chloroquine markedly reduced the uptake of 14C. Component analysis of 14C efflux curves indicated that this decrease occurred mainly within the slower of two washout components. Addition of metiamide (but not pyrilamine) to the bathing solution decreased 14C-histamine uptake, and exposure to metiamide during the washout of 14C-histamine decreased the rate of efflux. These effects of metiamide on 14C-histamine movements can be explained in terms of an altered ability of rabbit aortic smooth muscle to accumulate histamine at some cellular site or store.

Interactions between several rare earth ions and calcium ion in vascular smooth muscle

The effects of lutetium (Lu+++), europium (Eu+++) and neodymium (Nd+++) on 45Ca distribution, 45Ca movements and contractions were examined in rabbit aortic smooth muscle. Tension responses to norepinephrine were markedly inhibited by all three rare earth ions; K+-induced responses and those to histamine were partially blocked. Addition of 1.5 mM Lu+++, Eu+++ or Nd+++ to the bathing solution reduced 45Ca uptake (Nd+++ greater than Eu+++ greater than greater than Lu+++), produced a maintained increase in 45Ca efflux from strips of media-intimal layer washed out in a 0-Ca++ solution (Nd+++ greater than Eu+++ greater than Lu+++), and, when present during 45Ca incubation (before 45Ca washout), altered the release of 45Ca elicited by addition of 1.5 mM Ca++ during the 45Ca washout (inhibition by Nd+++ greater than Eu+++ greater than Lu+++). The 3-fold greater uptake of 45Ca in a 0-Ca++ and 1.5 mM Lu+++ solution than in an equivalent Sr++ solution results from a decreased effect of Lu+++ upon the slower 45Ca washout component. The actions of Lu+++ were quantitatively similar to those of low La+++ concentrations (0.05-0.10 mM), whereas those of Nd+++ and Eu+++ resembled effects obtained with equimolar concentrations of La+++. Thus, the three rare earth ions produce qualitatively similar alterations in 45Ca uptake and superficial binding. The difference observed can be attributed to variations in their affinity for superficial Ca++ binding sites and in their ability to block Ca++ uptake.

Differential inhibitory effect of neomycin on contractile responses of various canine arteries

The influence of neomycin on vascular smooth muscle contractile responses was examined in different isolated arterial preparations of the dog. Prior exposure (5 minutes) to 7 mM neomycin decreased contractile responses elicited with norepinephrine (NE, 0.6 muM) or KC1 (K-+, 80 nM) in helical strips of canine aortae (Ao) and femoral (F), carotid (Cd), renal (R), superior mesenteric (Sm), terminal mesenteric (Tm) and coronary (Cr) arteries. Addition of neomycin subsequent to NE-induced contractile responses depressed tension responses of the F, Cd, R, Sm and Tm arteries but had little or no effect on the Ao. However, after contractions had been elicited with K-+, neomycin had no effect on tension responses of the Ao, F, Cd, R or Sm arteries but depressed contractions of the Cr and Tm arterial strips. Preincubation with neomycin (0.7-3.5 mM) produced a concentration-related inhibition of contractile responses elicited in Tm arterial strips by addition of calcium ions (Ca-++; 1.6 mM) to a Ca-++-free depolarizing solution; conversely, subsequent addition of neomycin had no effect on maintained Ca-++ contractures. In constant flow-perfused terminal mesenteric arterial branches, neomycin (0.5-4.0 mM) produced a concentration-related antagonism of pressor responses elicited with NE (1-8 mug) or K-+ (40 mM). The inhibitory action of neomycin on K-+-induced pressor responses was inversely related to the Ca-++ concentration of the perfusion fluid. However, inhibition of NE pressor responses by neomycin did not appear to be related to the Ca-++ concentration. The differential inhibitory action of neomycin on contractions induced by NE and K-+ in various canine arteries suggests that different vascular beds vary in the manner in which Ca-++ is bound and subsequently utilized by stimulatory agents to elicit tension changes.

Effects of neomycin on 45Ca binding and distribution in canine arteries

The effects of neomycin (7.0 mM) on 45Ca movements and distribution were investigated in canine aortae and in canine carotid and terminal mesenteric arteries. Uptake of 45Ca was measured in calcium-free solution; the 45Ca tissue spaces in the carotid and terminal mesenteric arteries were 2--4 times greater than those observed in the aorta. Exposure of the aortae and the terminal mesenteric arteries to 1.5 mM Ca++ during the washout elicited large increases in 45Ca efflux in both preparations (increase in terminal mesenteric greater than aorta). Moreover, in all three arterial preparations, neomycin reduced 45Ca uptake and induced a sustained increase in 45Ca efflux (effects on terminal mesenteric larger than or equal to carotid greater than aorta). The terminal mesenteric and carotid arteries may accumulate and bind 45Ca at superficial membrane sites (readily exchangeable 45Ca) to a greater degree than does the aorta. If Ca++ located at these membrane sites contributes directly to the maintenance of mechanical responsiveness, then agents which alter membrane binding of Ca++ (e.g. neomycin) may exert a stronger action on these highly reactive vessels. Thus, contractile responsiveness in peripheral arteries may depend upon depots of superficially bound Ca++ to a greater degree than in the more centrally located aorta.

Effects of added or substituted potassium ion on 45 Ca movements in rabbit aortic smooth muscle

The effects of elevated potassium ion (K + ) concentration on radioactive calcium ( 45 Ca) movements and distribution were investigated in media-intimal strips prepared from rabbit aortic smooth muscle. 45 Ca uptake was measured in either normal (1.5 mM Ca 2+ ) or low-Ca (0.1 mM Ca 2+ ) solutions. In low-Ca solutions, elevating the K + concentration either by substituting equimolar (165.4 mM) K + for sodium (Na + ) (substituted-K solution) or by increasing K + concentration to 80 mM (added-K solution) increased the 45 Ca uptake. Exposure of the muscle strips to high K + concentrations during washout of 45 Ca decreased the 45 Ca efflux into either zero-Ca or low-Ca bathing solutions. Moreover, increased K + concentration elicited its effects in the presence or the absence of Na + . The decrease in 45 Ca efflux induced by substituted-K solution was also obtained in the presence of ethylenediaminetetraacetic acid (EDTA), but prior incubation of muscles with 1.5 mM strontium (Sr 2+ ) plus 45 Ca prevented this decrease in 45 Ca efflux. It would appear that the 45 Ca affected by high K + concentrations is at Sr-sensitive sites which are inaccessible to EDTA. If 45 Ca at these sites contributes directly to 45 Ca efflux, a shift of some of this 45 Ca to less superficial cellular sites might be responsible for the decreased efflux of 45 Ca observed in the presence of increased K + concentration.