Slow-reacting substance from alveolar macrophages--a mechanism of asthma?

The effects of alveolar macrophages on bronchial reactivity were studied in vitro to determine whether these cells could provide a pathogenetic link between cellular components of the inflammatory response, chemical medication of smooth muscle contraction and possible local mechanism of asthma. Alveolar macrophages harvested from rabbit lungs produced consistent and prolonged contractile responses in guinea-pig tracheal rings. The contractile material had the pharmacological and physical properties of slow-reacting substance (SRS) and, in particular, it was completely antagonized by minute concentrations (5 ng/ml) of a specific SRS antagonist, FPL 55712. The average contractile response per 10(6) macrophages was quantitatively equivalent to that produced by 76 ng methacholine. These findings not only support the view that local mechanisms may be of relevance in the pathogenesis of asthma, but could also have possible implications for therapy.     

Studies on cytosolic superoxide dismutase from intestinal mucosa

CuZn superoxide dismutase from monkey (Macaca radiata) intestinal mucosa was purified to homogenity. The enzyme showed a subunit molecular weight of 16000. The enzyme preparation from intestinal mucosa of rat, rabbit, guinea-pig and monkey was distinctly different in electrophoretic mobility and in elution profile on ion-exchange chromatography, possibly due to their difference in charge. The difference may not be due to glycosylation, since the enzyme was not stained for glycoprotein. Polyclonal antibody against purified monkey enzyme inhibited the activity of intestinal CuZn superoxide dismutase from rat, rabbit and guinea-pig. Thus it appears that intestinal CuZn superoxide dismutases from different sources, despite being similar in immunological and other properties, differ in certain amino acids and hence in charge.     

Characterization of bradykinin receptors in peripheral organs.

Bradykinin (BK) and related kinins are potent stimulants of the rabbit jugular vein, the hamster urinary bladder, and the guinea pig trachea. The characterization of kinin receptors in these tissues was made with agonists and antagonists. Results obtained with agonists indicate that bradykinin and kallidin are much more active than des-Arg9-BK and suggest the presence of B2 receptors in the three organs. Some new agonists were also tested and the BK analogue, [Hyp3,Tyr(Me)8]BK, was found to be a potent and selective stimulant of the three preparations, with pD2 values of 8.56, 8.00, and 8.39, respectively, but inactive on the rabbit aorta (a B1-receptor system). Contractile effects of kinins in the rabbit jugular vein and hamster urinary bladder were reduced or eliminated by B2-receptor antagonists but at different concentration levels; e.g., acetyl-D-Arg[Hyp3,D-Phe7]BK showed pA2 values of 7.78 on the rabbit jugular vein but only 5.72 on hamster urinary bladder. This compound contracted the guinea-pig trachea and was found to be inactive as an antagonist on this preparation. Contractions of the hamster urinary bladder and the guinea-pig trachea in response to bradykinin were markedly reduced or eliminated by indomethacin and by BW 755C, while those of the rabbit jugular vein were not modified. The present findings indicate that the myotropic effect of kinins on the rabbit jugular vein depends on the activation of B2 receptors and suggest that B2 receptors are largely responsible also for the response of the hamster urinary bladder. B2 receptors and (or) a nonreceptor mechanism appear to be involved in the stimulant effects of the kinin agonists and some antagonists in the guinea-pig trachea.     

Nicotine potentiates the neurogenic contractile response of rabbit bladder tissue via nicotinic acetylcholine receptors: nitric oxide and prostaglandins have no role in this process

Nicotine, a nicotinic acetylcholine receptors (nAChRs) agonist, has a role in modulation of the neurotransmitter release following nerve stimulation in both the central and peripheral nervous systems. The aim of this study was to determine whether electrical field stimulation (EFS)-evoked contractions are altered in rabbit bladder in the presence of nicotine and, if an alteration occurs, to investigate the effects of nitric oxide and prostaglandins on nicotine-induced alternation in isolated rabbit bladder. EFS-evoked contractile responses from rabbit bladder obtained were recorded with isometric force displacement transducers. Nicotine was added to preparations at various concentrations. The effects of hexamethonium, cadmium (Cd(2+)), indomethacin and N-nitro-L-arginine methyl ester (L-NAME) were tested on the EFS-evoked contractions in the presence of nicotine. Nicotine led to a dose-dependent increase in the amplitude of the EFS-evoked contractile responses. Cd(2+) and hexamethonium inhibited the nicotine-induced increase in EFS-evoked responses, whereas indomethacin and L-NAME had no effect. In conclusion, nicotine increased the EFS-evoked contractile responses possibly by facilitating release of neurotransmitters from nerve terminals by a mechanism dependent on the influx of Ca(2+) from voltage-gated Ca(2+) channels (VGCCs) via activation of nAChRs in isolated rabbit bladder. Nitric oxide and prostaglandins do not have a physiological role in the regulation of neurotransmitter release.     

Species comparison of renal proteolytic activity for human myelin basic protein peptide 43-88

1. A species comparison was conducted on the proteolytic activity in human, dog, rabbit, guinea-pig and rat kidney which can degrade human myelin basic protein peptide 43-88. 2. In rat kidney the degrading activity occurred over a pH range of 4-11.5 with the greatest activities at pH 5 and 9. The peptide degrading activity in human, dog, rabbit and guinea-pig kidney was considerably less than in the rat and occurred predominantly at pH 7 with lesser activity at pH 9. 3. The effects of inhibitors of proteolytic enzymes indicated that the peptide degrading activities at the same two pH's of dog, rabbit and guinea-pig were similar to one another but differed from that of human. 4. These results indicate that the activity for degrading a potential autoantigenic material is widespread in renal tissue among different species and that different enzymes are involved. More generally, these findings suggest that renal proteinases differ among commonly used laboratory animals and also differ from the human enzymes.     

Contractions in bronchial musculature of rabbit and man in response to various drugs

1. The contractile behaviour of rabbit and man bronchial musculature has been tested in response to some commonly used substrates for cholinesterase, histamine and adrenaline by the kymograph technique. 2. The sensitivity of the smooth bronchial musculature from both rabbit and man was found to be highest for acetylcholine and acetyl-beta-methylcholine (6.3 X 10(-8) M) and lowest for butyrylcholine (6.3 X 10(-6) M). 3. The smooth bronchial musculature of man was slightly more sensitive to histamine and adrenaline than that of the rabbit. 4. The results indicate that the contractile behaviour in the smooth bronchial musculature of rabbit and man is remarkably similar.     

Effects of chronic nicotine treatment on nicotinic receptors in the rabbit urinary bladder

Nicotine induced a phasic contraction in the rabbit urinary bladder. The response was abolished by hexamethonium and partially reduced by atropine and capsaicin. Simultaneous atropine and capsaicin treatment did not abolish the contraction. These findings suggest that the response to nicotine is due to acetylcholine, tachykinins, and unknown mediator release. In contrast, nicotine-induced contraction diminished following the chronic nicotine treatment without a change of its pharmacological properties. These results suggest the possibility that chronic nicotine treatment causes a decrease in nicotinic receptor numbers. Therefore, the binding properties of (-)-[3H]nicotine on rabbit urinary detrusor muscle membrane fractions were studied to evaluate the effects of chronic nicotine treatment on nicotinic receptors. Specific (-)-[3H]nicotine binding reached saturation and Scatchard plots were curvilinear, suggesting the existence of two different affinity sites for (-)-[3H]nicotine. Dissociation constants (KD) and maximum binding sites (Bmax) were KD1 = 4.91 +/- 1.88 nM, Bmax1 = 2.42 +/- 0.22 fmol/mg protein and KD2 = 263 +/- 56 nM, Bmax2 = 25.0 +/- 4.3 fmol/mg protein. In urinary bladder membrane fractions from chronic nicotine-treated rabbits, KD and Bmax values were KD1 = 3.96 +/- 0.38 nM, Bmax1 = 1.07 +/- 0.25 fmol/mg protein and KD2 = 249 +/- 12 nM, Bmax2 = 10.8 +/- 1.5 fmol/mg protein. Dissociation constants for both sites following chronic nicotine treatment did not change but maximum binding site numbers for both sites significantly decreased (p less than 0.05). These results suggest that the decrease in contractile response evoked by nicotine after chronic nicotine treatment in rabbit urinary bladder is due to a decrease in numbers of nicotinic receptors.     

Immunochemical comparisons among myelin basic proteins.

1. The relationships among myelin encephalitogenic or basic proteins were immunochemically examined. 2. Rabbit antisera to myelin basic proteins isolated from chicken, rabbit, bovine, guinea-pig, and human brain specimens were prepared. By quantitative microcomplement fixation these rabbit antisera were used to measure cross-reactions among the myelin basic proteins of the turtle, chicken, rat, rabbit, cow, pig, sheep, dog, guinea-pig, monkey and human. 3. A spectrum of cross-reactivities was detected even though some cross-reactivity persisted across major phylogenetic barriers. Varying, but sometimes marked, differences existed in reactivities of the small and large basic proteins of the rat. Reciprocity of cross-reactivities among basic proteins was inconstant. 4. This study demonstrates the range of immunochemical cross-reactivities among myelin basic proteins and the sensitivity of quantitative microcomplement fixation in assessing such antigenic or conformational differences.     

Vascular actions of thrombin receptor peptide.

We have examined the action of the thrombin receptor-derived polypeptide, S42FLLRNPNDKYEPF55 (TRP 42-55), in rat and guinea pig aortic rings and helical arterial strips, and we have compared the actions of the peptide with those of thrombin. In rat preparations, both TRP 42-55 and thrombin caused a concentration-dependent endothelium-dependent relaxation that was blocked by N omega-nitro-L-arginine methyl ester; the relaxation response of the intact rat aortic strip preparation to concentrations of the peptide in the range 30-60 micrograms/mL (17-34 microM) was equivalent to the response to 0.03-0.1 U/mL of thrombin (about 0.3-0.9 nM), yielding a potency ratio (TRP 42-55:thrombin) of about 38,000:1. In contrast with the complete desensitization of thrombin-treated rat aortic preparations to a second administration of the enzyme, the rat aortic tissue was not desensitized by repeated exposures to TRP 42-55 and remained responsive to the peptide even after treatment of the tissue by thrombin. In contrast with the rat aortic tissue, in either intact or endothelium-free guinea pig aortic preparations both TRP 42-55 and thrombin caused a concentration-dependent endothelium-independent contraction. The contractile action of 60 micrograms/mL of receptor peptide (34 microM) in guinea pig aortic strip preparations was equivalent to the contractile action of 0.1-0.3 U/mL thrombin (0.9-3 nM), yielding a potency ratio of about 17,000:1. In guinea pig aortic preparations with an intact endothelium that were precontracted with noradrenaline, neither thrombin nor TRP42-55 caused relaxation, whereas substance P did so.(ABSTRACT TRUNCATED AT 250 WORDS)     

Glutamine synthetase in kidneys of monkey and man.

1. The synthesis of gamma-glutamylhydroxamate from glutamate and hydroxylamine has been utilized as an approximation of glutamine synthetase activity in kidneys of rabbit, rat, dog, monkey and man. 2. Kidneys of rabbit contain glutamine synthetase in high activity; those of rat, in intermediate activity; and those of dog, monkey and man, in negligible activity. 3. No more enzyme is present in kidneys of the latter two species than in those of the dog, in which the enzyme is generally considered to be absent.     

A study of Sertoli-spermatid tubulobulbar complexes in selected mammals

Tubulobulbar complexes (TBCs) were found in nine mammalian species (opossum, vole, guinea-pig, mouse, hamster, rabbit, dog, monkey and human) primarily originating from the plasma membrane overlying the acrosome of late spermatids. Fewer complexes (4–10) were noted in these species than has been previously reported for the rat (up to 24). TBCs were not seen emanating from round spermatids or those elongated spermatids located within the deep recesses of the Sertoli cell, but they appeared as the spermatids came to reside much closer to the tubular lumen in preparation for release. TBCs developed in areas deficient or lacking in Sertoli filaments and endoplasmic reticulum (ectoplasmic specialization). In general their structural configuration was similar to that shown in the rat, although minor differences were noted. Fine fibrils were observed connecting the distal portion of the spermatid tube with the Sertoli plasma membrane forming a bristle-coated pit. The length of TBCs from most species studied was 1–2 μm, whereas those of the opossum extended 6–8 μm into an apical Sertoli process. TBCs were degraded within the Sertoli cell by its lysosomes prior to sperm release, and for most species there was evidence indicating that formation of more than one generation of TBCs occurred. As sperm release approached, TBCs formed preferentially from the leading edge of spermatids with spatulate heads. The Sertoli cell gradually withdrew from around the spermatid head until only the tip of the head was embedded within the Sertoli cell. This region of contact frequently demonstrated TBCs. The proposed functions of TBCs are reviewed and discussed in light of these findings from other species.     

A pharmacological investigation of the biphasic nature of the contractile response of rabbit and rat vas deferens to field stimulation

It has been demonstrated previously with the vas deferens of the guinea-pig that the first and second phases of the contractile response to motor nerve stimulation are preferentially antagonized by the P₂-purinoceptor antagonist arylazido aminopropionyl ATP (ANAPP₃), and the α₁-adrenoceptor antagonist prazosin, respectively. We have now investigated the effect of the two antagonists on the biphasic contraction in the vas deferens of two other species; rabbit and rat. ANAPP₃, in a concentration which antagonized responses to exogenously applied ATP but not those to exogenous norepinephrine, preferentially reduced the initial phasic response of the rabbit vas deferens to motor nerve stimulation without significantly reducing the secondary, tonic phase of the response. Prazosin had the opposite effect; antagonizing the response to norepinephrine but not to ATP and reducing the tonic response to motor nerve stimulation without significantly reducing the initial phasic response. Results obtained with the rat vas deferens were similar. The present results combined with previous findings suggest that ATP and norepinephrine act as cotransmitters in the vas deferens of several species.     

Effect of nedocromil sodium on non-adrenergic, non-cholinergic neural responses in guinea pig bronchi in vitro.

OBJECTIVE: Nedocromil sodium (nedocromil) improves the clinical condition of asthmatic subjects but its mechanism of action is not fully understood. This study aimed to determine whether nedocromil alters the ability of contractile and relaxant non-adrenergic, non-cholinergic neural (NANC) responses to stabilise tone by inhibiting or potentiating these responses in bronchial smooth muscle and, if so, whether the action is on a pre- or postjunctional level. RESULTS: Nedocromil attenuated contractile but not relaxant NANC responses (elicited by electric field stimulation) significantly (P < 0.05) in guinea pig main bronchi in vitro. However, the ability of NANC responses to stabilise tone (convergence effect) was not significantly impaired by nedocromil. Furthermore, nedocromil did not significantly shift the concentration response curve (-log EC50) to neurokinin A (NKA), the dominating contractile NANC transmitter, or alter the maximum response to NKA (P > 0.05). Submaximum or maximum contractile responses to histamine were not markedly affected by nedocromil (P > 0.05). CONCLUSIONS: Nedocromil exerts selective neural inhibition of the contractile but not of the relaxant NANC responses on a pre-junctional level in bronchial smooth muscle. Nedocromil does not, however, markedly impair the ability of NANC response to stabilise bronchial smooth muscle tone.     

Chemotactic potency of recombinant human neutrophil attractant/activation protein-1 (interleukin-8) for polymorphonuclear leukocytes of different species

In order to establish the species cross-reactivity of the human neutrophil attractant/activation protein-1 (interleukin-8, NAP-1/IL-8) and find which experimental species are responsive to the human cytokine, blood polymorphonuclear leukocytes (PNMLs) were isolated from chicken, dog, goat, guinea-pig, monkey, mouse, pig, rabbit, and rat and their in vitro migration in response to this cytokine was investigated. PMNLs from all of the tested species migrated in response to recombinant human NAP-1/IL-8 (rhNAP-1/IL-8). The potency of rhNAP-1/IL-8 for the PMNLs of different species varied and was considerably lower than its potency for human cells. The morphological study combined with the leukocyte enumeration in the intradermal rhNAP-1/IL-8 injection sites established an in vivo proinflammatory potency of rhNAP-1/IL-8 for rabbit and rat that was comparable to the observed in vitro chemotactic potency of rhNAP-1/IL-8 for neutrophils of these species.     

Functional identification of epithelial and smooth muscle histamine-dependent relaxing mechanisms in the bovine trachea,but not in bronchi

Theoretically, the overall effect of histamine on respiratory smooth muscle is the result of a subtle balance of contraction and relaxation. The aim of the study was to identify histamine type 2 (H2) and 3 (H3) receptor-dependent relaxing mechanisms in the contractile elements of the bovine tracheobronchial tree. In bronchial preparations, histamine induced very weak contractions, which were not exacerbated with the H2-antagonist cimetidine. Moreover, precontracted bronchial rings never relaxed in response to cumulative doses of histamine or amthamine (H2-agonist). In intact tracheal preparations, histamine induced strong contractions that were exacerbated by cimetidine (E(max): +17.2+/-6.6%) but not by thioperamide (H3-antagonist). Precontracted tracheal bundles did not relax in response to cumulative doses of the H3-agonist R-alpha-methylhistamine. The tracheal contractile response was higher in denuded compared to intact preparations (11.0+/-1.2 vs. 6.0+/-1.7 g). Cimetidine effect was dramatically potentiated in denuded tracheal strips (+40.0+/-11.7%). It is concluded that the weak response of bovine bronchi to histamine is due to a relative scarcity of H1 receptors on bronchial smooth muscle rather than to H2- or H3-dependent relaxation. In the bovine trachea, the smooth muscle possesses relaxing H2 but no H3 receptors. The epithelium exercises a relaxation, which is independent from H2 and H3 receptors.     

Lack of specific (3H) prazosin binding sites in dog and rabbit cerebral arteries

In order to explore the characteristics of alpha adrenergic receptors on cerebrovascular smooth muscle, specific binding sites for the alpha 1 adrenergic ligand, (3H) prazosin, were studied in blood vessel homogenates. No specific (3H) prazosin binding was found in either rabbit or dog cerebral arteries, but specific binding was demonstrated in the rabbit saphenous and ear arteries. In the ear artery 3H-prazosin binding was saturable with a Kd of 0.51 +/- 0.20 nM and a Bmax of 89 +/- 29 fmoles/mg protein. To confirm the adequacy of our membrane preparation, homogenates of both dog and rabbit cerebral arteries showed saturable specific binding with two different ligands: one for muscarinic receptors, [3H](-) quinuclidinyl benzilate (QNB) and one for alpha 2 adrenergic receptors, (3H) yohimbine. The results of these studies demonstrate a lack of alpha 1 adrenergic receptors on cerebral blood vessels, confirming functional studies showing only a weak contractile response to norepinephrine.     

Comparative regional distribution of angiotensin-I-converting enzyme in the rat, rabbit, dog, monkey and human kidneys

Kidney is the main source of the production of renin and angiotensin, while also being one of their main target organs. This study was designed to determine the regional distribution of angiotensin-I-converting enzyme (ACE) in the kidney using a biochemical approach. Interspecies variations were analyzed in human, monkey, rabbit, dog and rat kidneys. Kidney ACE content differed among species with decreasing contents as follows: rabbit greater than human greater than monkey greater than dog greater than rat. In rabbit, human, monkey and dog kidneys, we observed predominant cortical distribution of ACE compared with the medulla or papilla; median cortex/papilla ACE activity ratio was 19, 14, 9 and 7 for the rabbit, human, dog and monkey, respectively. In rat kidney, ACE predominantly distributes in the outer medulla, while cortex ACE content appears to be low. The difference in ACE distribution in the rat kidney and to a lesser extent in the dog kidney when compared to rabbit, monkey or man should be taken into account when extrapolating to the human renal hemodynamic studies, which are frequently performed in rats or dogs.     

Comparative study of cardiac electrophysiological effects of atrial natriuretic peptide

The effects of atrial natriuretic peptide (ANP) on action potential characteristics were studied in various (human, rabbit, guinea-pig) atrial and guinea-pig right ventricular papillary muscles. ANP (1–100 nM) did not modify the resting membrane potential nor the maximum rate of depolarization phase (V_max). Up to 10 nM, ANP dose-dependently decreased the action potential amplitude both in guinea-pig atrial and ventricular muscles, but it did not affect this parameter in the other atrial preparations. ANP caused a dose-dependent, marked decrease of action potential duration (APD) in practically every cardiac preparation studied (exception of guinea-pig left atrium). The strongest effect on APD can be observed in human atrial and guinea-pig ventricular fibers. The K⁺ channel blocker 4-aminopyridine (1 mM) and the ATP-dependent K⁺ channel inhibitor glibenclamide (10Nl) prevented the effect of ANP on APD in both ventricular atrial preparations. ANP prevented the appearance of isoprenaline (0.5 M) induced slow AP in K⁺ depolarized myocardium. The present data suggest that ANP may inhibit the slow inward Ca²⁺ channel activity and facilitate the K⁺ channel activity.     

Hypertensive factor: calcium stimulatory activity obtained from different tissues and animal species

It was recently shown that a peptide (hypertensive factor, HF) isolated from erythrocyte hemolysates from spontaneously hypertensive rats induced a prolonged elevation of blood pressure in normotensive rats. In addition, the peptide produced a marked stimulation of the in vitro uptake of lanthanum-resistant calcium by the aortae and enhanced the contractile response of aortic rings to constrictor agents. The present report describes findings of calcium stimulatory activity, enhancement of contractile function, or pressor activity in extracts of homogenates from several tissues of the rat and from erythrocyte hemolysates of several mammalian species. Significant stimulation of calcium uptake in aortic rings was obtained with preparations from rat brain, liver, and kidney. The activity per weight of tissue was similar for brain and kidney (approximately 2 units/g), while liver exhibited somewhat higher concentrations (4 units/g). The diffusate of cardiac tissue did not significantly alter in vitro calcium uptake by aortae. The injection of the cardiac and liver diffusates into normotensive Wistar-Kyoto rats produced slight (10 Torr) (1 Torr = 133.3Pa) and moderate (25 Torr) elevations of blood pressure, respectively. Finally, a peptide purified from homogenates of rat brain by the protocol developed for the purification of HF from erythrocytes was shown to significantly enhance the contractile response of aortic rings to K+ and norepinephrine. Diffusates of erythrocytes from the rat, rabbit, dog, and guinea pig each caused a significant stimulation of calcium uptake and contained approximately the same level of activity (500 units/L of whole blood). Diffusates prepared from outdated human erythrocytes had no significant effect on calcium uptake, whereas those of freshly drawn samples exhibited high levels of activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Non-adrenergic, non-cholinergic nerves in mammalian airways: their function and the role of purines

1. Relaxations to field stimulation of sympathetic nerves were found in the guinea-pig trachea only. 2. Relaxations to field stimulation of non-adrenergic inhibitory nerves were found in the larger airways of human, monkey, guinea-pig and rabbit, but not rat. 3. Lung strips from all the mammals failed to respond to sympathetic or non-adrenergic inhibitory nerve stimulation. 4. Inhibitory beta-adrenoceptors were demonstrated in the proximal airways of all species except rabbit. 5. Of the fine airways examined, beta-adrenoceptors only were found in guinea-pig and alpha-adrenoceptors only in rabbit while rat, monkey and human tissues contained mixed populations of both receptors. 6. Adenosine is a likely candidate for the neurotransmitter in the non-adrenergic inhibitory nerves. Inhibitory receptors for adenosine were present in guinea-pig trachea although receptors for ATP are probably lacking.