Activation Of Smooth Muscle Contraction Research Articles

Evidence against cholinergic mediation of the effect of angiotensin II on the guinea pig ileum.

The belief that the smooth muscle contracting activity of angiotensin II (angiotensin) in the guinea pig ileum is partly mediated by release of acetylcholine was reexamined, with the following results. 1. Atropine did not reduce the maximum contraction produced by angiotensin, although it caused a shift to the right of the log dose-response curve (dose ratio = 2.2). A similar shift was observed with histamine, bradykinin and BaCl2. 2. A moderate potentiation of angiotensin by eserine was also observed, which was similarly found for the other agonists. 3. A previous report that atropine blocks the fast (phasic) component of the isometric response of the ileum to angiotensin was not confirmed. The disappearance of the phasic component was found to be due to a tachyphylactic change in the response. 4. Depolarization by high doses of nicotine, and inhibition of acetylcholine synthesis by hemicholinium, did not affect the response to angiotensin. 5. Ilei in which the intramural ganglia had been destroyed by incubation at 4 degrees 48-56 h responed maximally to angiotensin, without loss of the phasic component of the response. It is concluded that the available evidence does not support the participation of a cholinergic mechanism in the effect of angiotensin upon the guinea pig ileum.

Uptake and inactivation of a-type prostaglandins by human red cells

Incubation of A type prostaglandins with whole blood or washed red cells at 37°C converted them to more polar products with negligible vasodepressor and smooth muscle-contracting activities. This conversion did not occur in platelet-rich plasma. Uptake of the prostaglandins by red cells was demonstrated at both 4°C and 37°C. The data suggest 1) that if PGA is released from tissues into the blood stream or is administered for therapeutic purposes, its biological activity would be diminished by human red cells, and 2) that development of an assay for PGA in blood should take into account its uptake and metabolism by human red cells.

Release of Slow Reacting Substance of Anaphylaxis from Human Leukocytes

Abstract Mediators of immediate hypersensitivity were released from human leukocytes by means of allergen challenge. Leukocytes from 12 consecutive donors were challenged with allergens to which these donors were clinically sensitive. In all, histamine and a second substance (SRS-Aleuk) which caused prolonged contraction of guinea pig ileum, were released. No SRS-Aleuk was obtained without allergen-challenge, and none was observed from non-atopic leukocytes challenged with the same allergens. The time of release after addition of allergens and the allergen dose-response curves for release of both histamine and SRS-Aleuk were quite similar. SRS-Aleuk was synthesized de novo after allergen-challenge since this factor was not demonstrated in disrupted cells. SRS-Aleuk was soluble in 80% ethanol and was not destroyed by base hydrolysis. The smooth muscle contracting activity of SRS-Aleuk resembled that of slow reacting substance of anaphylaxis (SRS-A) obtained from human lung and rat peritoneal cells, but was different from histamine, bradykinin, serotonin, and prostaglandin E1 and F2α. Preliminary studies suggest that both histamine and SRS-Aleuk are synthesized by human basophils. We conclude that SRS-A is generated by human leukocytes as well as human lung and nasal polyps, and suggest that this mediator may play an important role in the pathogenesis of human immediate hypersensitivity reactions.

Kam semen: Their role in the immune rejection of the nematode Nippostrongylus brasiliensis from the small intestine of rats

Recent work has established that chloroform extracts of ram semen and fractions of these extracts accelerate rejection of the nematode, Nippostrongylus brasiliensis, from the intestine of rats when injected intra-duodenally on day 6 of a primary infection (6). It was also shown that the administration of aspirin and d-propoxyphene hydrochloride (d-PP), potent inhibitors of prostaglandin action (7, 8), prevented the expulsion of worms which normally occurs between days 10 and 16 of a primary infection with N. brasiliensis. In the present study, we have established that there is a direct correlation between smooth muscle contracting activity and the capacity of individual semen fractions to accelerate worm expulsion. Methylation destroyed both smooth muscle contracting activity and the capacity of semen fractions to cause worm expulsion. Contraction of smooth muscle induced by the most active semen fraction (S.A.F. 1) was not inhibited by the amine antagonists mepyramine maleate and bromylsergic acid diethylamide. In addition, contractions induced in rabbit duodenum segments by 5-hydroxytryptamine were not inhibited by aspirin. These findings indicate that the semen fractions do not contain physiologically significant levels of the amines, histamine and 5-hydroxytryptamine, and this suggests that the capacity of semen fractions to cause worm expulsion is due to prostaglandins. This conclusion is supported by the observation that the most active fraction S.A.F. 1 contained bands with R F values which corresponded with the R F values of synthetic prostaglandins in thin layer chromatography. Furthermore, the intra-duodenal injection of synthetic prostaglandins also caused worm expulsion.

Structure determinations and synthesis of pharmacologically active phospholipids from kidney and intestine.

AbstractThe chemical structures of an acidic phospholipid originally isolated from equine intestine by Vogt and of a phospholipid isolated from rabbit kidney medulla by Walaszek are shown by total synthesis to be similar mixtures of 2‐alkyl (and alkenyl)‐4‐hydroxymethyl‐1,3‐dioxolane‐dihydrogen phosphate esters. In these materials, the alkyl residues derive primarily from oleyl, palmityl and linoleyl aldehydes. The smooth muscle contracting activity observed in the natural substances is shown to reside exclusively in the oleyl aldehyde derivative.

Urticaria Pigmentosa and Factitious Urticaria

A method of continuous in vivo subcutaneous perfusion using Tyrode solution which permits direct analysis of pharmacological agents released in inflamed human skin is described. An examination was carried out using bioassay with three isolated organ preparations and spectrofluorometry. In dermographic skin of patients with urticaria pigmentosa the perfusate was consistently found to contain histamine. Additionally, smooth muscle-contracting activity against the rat uterus was detected but this was shown not to be due to bradykinin, histamine, serotonin, or acetylcholine. In urticaria factitia histamine was regularly recovered from the perfusate; bradykinin was detected in perfusates from only two of eight subjects studied. Similar experiments carried out in a group of control subjects revealed evidence of low concentrations of kinins in a minority of subjects but no other pharmacological activity was found.

Urticaria pigmentosa and factitious urticaria. Direct evidence for release of histamine and other smooth muscle-contracting agents in dermographic skin.

A method of continuous in vivo subcutaneous perfusion using Tyrode solution which permits direct analysis of pharmacological agents released in inflamed human skin is described. An examination was carried out using bioassay with three isolated organ preparations and spectrofluorometry. In dermographic skin of patients with urticaria pigmentosa the perfusate was consistently found to contain histamine. Additionally, smooth muscle-contracting activity against the rat uterus was detected but this was shown not to be due to bradykinin, histamine, serotonin, or acetylcholine. In urticaria factitia histamine was regularly recovered from the perfusate; bradykinin was detected in perfusates from only two of eight subjects studied. Similar experiments carried out in a group of control subjects revealed evidence of low concentrations of kinins in a minority of subjects but no other pharmacological activity was found.

The responses of the skin to tetrahydrofurfuryl nicotinate (trafuril) studied by continuous skin perfusion.

SUMMARY.— The responses to topical application of tetrahydrofurfuryl nicotinate (Trafuril) cream were studied using a continuous skin perfusion method in clinically uninvolved skin of patients with chronic urticaria and in control patients. Trafuril causes inflammation but also renders the skin susceptible to dermographism. In non-urticarial subjects little pharmacological activity was detected during Trafuril inflammation or after stroking the skin to induce dermographism. This suggests that Trafuril causes inflammation by a direct effect on the cutaneous vasculature. By contrast in urticarial patients histamine was recovered more frequently than in non-urticarial patients during Trafuril inflammation, both before and after the skin was stroked. Perfusates from urticarial subjects also contained unidentified smooth muscle contracting activity which was not due to histamine, kinins, serotonin or acetyl choline. These results suggest that the skin of patients with chronic urticaria releases histamine and some other pharmacological agents more readily than that of normal subjects in response to inflammation producing stimuli.

Isolation of a fragment (C3a) of the third component of human complement containing anaphylatoxin and chemotactic activity and description of an anaphylatoxin inactivator of human serum.

A small fragment of C3, called C3a, which has smooth muscle contracting activity, was isolated by three different methods. At pH 8.6, C3a behaved as cation, and using the Archibald method, its mol wt was determined to be 7000. A specific antiserum to C3a showed the fragment to be antigenically distinct from the rest of the C3 molecule, i.e., the C3b portion. The same antiserum and an anti-whole C3 were able to inhibit the biologic activity of C3a. In addition to anaphylatoxin activity, leukocyte chemotactic activity was shown to reside in C3a. Treatment with trypsin caused the cationic fragment to become anionic and abolished the anaphylatoxin but not the chemotactic activity. C3a fragments with identical biologic activity and comparable cationic properties, as determined by acid disc electrophoresis, were obtained by treatment of C3 with C3 convertase, C3 inactivator complex, trypsin, and plasmin. Thrombin produced a similar C3 fragment which was inactive. It was concluded that C3a corresponds to an unusually basic portion of C3 which may be liberated by attack of a variety of enzymes on a highly susceptible region of the native C3 molecule. C3b was cleaved by trypsin and less efficiently by thrombin or plasmin into two antigenically distinct pieces: the larger C3c fragment corresponding to beta(1A) and the smaller C3d fragment to alpha(2D) of aged serum. The c- and the d-fragments were separated and characterized. Isolated C3a rapidly lost its anaphylatoxin activity when treated with small amounts of a partially purified, thermolabile 10S alpha-pseudoglobulin of human serum. The conditions of inactivation suggested an enzymatic reaction. The anaphylatoxin inactivator also destroyed the activity of C5-derived anaphylatoxin and of lysyl bradykinin.

Effects of prostaglandins E1, E2, A1, and F1-alpha on isolated vascular smooth muscle

Effects of prostaglandins E1, E2, A1, and F1-alpha on isolated vascular smooth muscle

Isolation and amino acid composition of bradykinin released by venom of Bothrops Jararaca from bovine plasma

Bradykinin was prepared from partially heat- and acid-denatured bovine plasma by action of Bothrops jararaca venom. Purification was performed by ion-exchange chromatography with Amberlite IRC-50 (XE-64), paper electrophoresis and paper chromatography. Determinations of purity and identification were carried out with the DNP-derivatives of amino acids in the hydrolyzate of the peptide. A molar ratio of 1:1.1:1.7:2.8:1.9 was obtained for the DNP-derivatives of serine, glycine, phenylalanine, proline and arginine (serine = 1) from the purified peptide fraction. Comparison between the synthetic nonapeptide and this natural bradykinin showed close similarity as regards their smooth muscle contracting and hypotensive activities. The evidence presented suggests the structural identity between the snake venom- and trypsin-released bradykinin and the synthetic nonapeptide Arg·Pro·Pro·Gly·Phe·Ser·Pro·Phe·Arg· (all L-configuration).