32 research outputs found
Bioassay of vasopressin on the rabbit isolated urinary bladder.
No full textThe rabbit isolated urinary bladder contracted in the presence of Lys8-vasopressin from threshold concentrations of 5 to 30 μ ml−1 (0·02 to 0·11 ng ml−1). Responses were proportional to the dose used. The tissue gave satisfactory results either fresh or after storage for several days in cold Tyrode or Krebs solution (3–4°). The preparation also contracted in the presence of oxytocin, but it was 7 to 20 times less sensitive to this peptide. A number of other peptides and amines known to stimulate smooth muscle showed low activity on the rabbit urinary bladder and, occasionally, intense tachyphylaxis
The use of preparations of urinary bladder smooth muscle for bioassay of and discrimination between polypeptides.
No full textEleven polypeptides, two prostaglandins and three amines were assayed, in parallel, by measurement of their spasmogenic effect on the isolated urinary bladder of eight animal species, the in situ bladder of three species and the isolated ureter of three species. Several of the smooth muscle preparations examined proved to be sensitive and suitable test-objects for the quantitative bioassay of different peptides. At the same time they appeared to be useful for discriminating not only between peptides belonging to different groups, but also between members of the same peptide family. It is tentatively suggested that biogenic peptides may interfere in the physiological control of motility and tone of the urinary tract smooth muscle
The action of polypeptides, amines and prostaglandins on isolated smooth muscle preparations of seminal vesicles and deferent ducts
No full textThe spasmogenic effect of 11 biogenic polypeptides, 2 prostaglandins and 3 amines was assayed, in parallel, on the isolated seminal vesicles and deferent ducts of the rat, guinea pig and hamster. The smooth muscle preparations were contracted by most of the examined compounds, but none of the preparations appeared to be particularly sensitive, and not infrequently bioassay was made difficult by tachyphylaxis. Thus, the smooth muscle preparations of the male genital tract, although containing receptors for biogenic polypeptides and amines, cannot be considered as test objects of first choice in the qualitative and quantitative bioassay of these compounds
Parallel bioassay of bombesin and litorin, a bombesin like peptide from the skin of Litoria aurea
No full textThe spectrum of biological activity exhibited by litorin, a bombesin‐like nonapeptide found in extracts of the skin of the Australian leptodactylid frog Litoria aurea was compared with that exhibited by the tetradecapeptide bombesin. Litorin proved to be more potent than bombesin on isolated smooth muscle preparations and on the urinary bladder in situ. However, it was less potent on dog systemic blood pressure and kidney vasculature, activation of the renin‐angiotensin system being slight or lacking. Gastrin release and acid secretion produced by litorin was more rapid in onset but less intense and less sustained than that elicited by bombesin. The same could be observed for pancreatic secretion. Gall bladder contraction stimulated by litorin was probably caused by a double action of the peptide, directly on the bladder smooth muscle, and indirectly by cholecystokinin release. In its effects on the myo‐electric activity of the dog duodenum (inhibition of spikes and increase in frequency of pacesetter potentials leading to the appearance of a sequence of slow and small potentials) litorin possessed approximately 50 to 70% of the activity of bombesin. 1975 British Pharmacological Societ
Parallel bioassay of 39 tachykinins on 11 smooth muscle preparations. Structure and receptor selectivity/affinity relationship
No full textParallel bioassay on smooth muscle preparations demonstrated that: all TKs having a neutral or basic residue at position 7 from the
C-terminus show a clear-cut preference for the NK1 TK receptor, reinforced by the presence of the aromatic doublet Phe-Phe or Phe-Tyr
(aromatic TKs); all aliphatic TKs (Phe-Ile/Val) having an acidic residue at position 7 show a clear-cut preference for NK2/NK3 receptors,
generally without selectivity for a single receptor. However, in aromatic TKs having the same acidic residue, the preference for NK2/NK3
receptors is weakened, with a more or less pronounced co-preference for the NK1 receptor. Amino acid substitutions in the C-terminal
tripeptide may influence receptor affinity
Neuropeptide Y release by pumiliotoxin-B in electrically stimulated mouse vas deferens: an immunohistochemical study
No full text(I.F.= 2,635
The tachykinin peptide family
No full textThe tachykinin peptide family certainly represents one of the largest peptide families described in the animal organism. So far, more than 40 tachykinins have been isolated from invertebrate (insects, worms, and molluscs), protochordate, and vertebrate (skin, gastrointestinal tract, peripheral and central nervous system) tissues. Substance P (SP), first identified by bioassay as early as 1931 but sequenced only in 1971, several years after the elucidation of the structure of eledoisin from molluscan tissues and of physalaemin from amphibian skin, may be considered as a prototype of the tachykinins. Hitherto, as many as 19 tachykinins have been isolated from amphibian integument, and eight additional peptides have been isolated from amphibian gut and brain. Counterparts of skin tachykinins in mammalian tissues are SP, neurokinin A, and neurokinin B. Three main receptor subtypes for the tachykinins have been identified (NK1, NK2, and NK3), but their number is probably destined to increase. It is obvious that the peripheral and central effects of the tachykinins may substantially vary depending on the activation of different receptor subtypes. Matters are further complicated by the frequent capacity of the single tachykinins to bind, although with different affinity, to more receptors. It has been recognized that tachykinins have a variety of effects in physiological and pathological conditions, and there is evidence suggesting intrinsic neuroprotective and neurodegenerative properties of these neuropeptides. This review provides an update on the current body of knowledge regarding tachykinin occurrence and distribution in the animal kingdom, from the lowest invertebrates to man, and the physiological and pharmacological actions of tachykinins outlining the pregnant importance of this large peptide family
