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Biomedical subjects

V Erspamer

Publications and source records attributed to V Erspamer.

At least 73 records · Page 4Linked to original sources
PubMed1980

Isolation and amino acid composition of sauvagine. An active polypeptide from methanol extracts of the skin of the South American frog Phyllomedusa sauvagei.

The skin of the South American frog Phyllomedusa sauvagei contains a new active polypeptide, sauvagine, which does not belong to any of the peptide families hitherto described in the amphibian skin. The purification procedure involved several successive steps: dialysis, precipitation with ethanol and acetone, gel filtration and ion exchange chromatography. Two forms of sauvagine were separated. The major component (sauvagine I) was submitted to acid hydrolysis. The sauvagine molecule appeared to possess clear hydrophobic characteristics and to consist of a straight chain of 40 amino acid residues, among which the glutamyl-, aspartyl- leucyl- and isoleucyl-residues were particularly well represented. The elucidation of the amino acid sequence in the sauvagine molecule is in progress.

Amino Acids↗
PubMed1979

Amino acid composition and sequence of crinia-angiotensin, an angiotensin II-like endecapeptide from the skin of the Australian frog Crinia georgiana.

Methanol extracts of the skin of the Australian amphibian Crinia georgiana contain large amounts of crinia-angiotensin II, a new angiotensin II-like peptide. This differs sharply from the conventional octapeptide angiotensins II in having attached the tripeptide Ala-Pro-Gly- to the N-terminus, and having an Ile residue substituted for the Val residue at position 6 from the C-terminus. Small amounts of angiotensin-like peptides have been traced, by radioimmunoassay, in skin extracts of some other Crinia species.

Amino Acid Sequence↗
PubMed1979

Occurrence and polymorphism of bombesin-like peptides in the gastrointestinal tract of birds and mammals.

The gastrointestinal tract of mammals and birds, especially stomach and upper small intestine, contains bombesin-like peptides. This has been unequivocally demonstrated by radioimmunoassay and bioassay. Concentrations of bombesin-like activity may range from a few ng to 500-600 ng per g fresh tissue. Last values refer to the chicken proventriculus, which has been the object of a more thorough investigation. The bombesin-like peptide of the chicken proventriculus showed a marked heterogeneity. All forms probably stem from a pro-bombesin, a large precursor molecule which is insoluble in methanol, acetone, and even boiling water, but may be cleaved by acid hydrolysis. Methanol extracts contain at least two forms of the bombesin-like peptide; HCl extracts at least three forms; HCl extracts of the residue of methanol extraction at least four forms. Whereas some forms--for example, the methanol extractable forms--probably pre-exist in the tissue, other forms may be artefacts arising from acid treatment. The various forms may be distinguished from each other not only by their elution profile, but also by bioassay. In fact, though all forms show the activity spectrum characteristic for the amphibian bombesin-like peptides, they present considerable quantitative differences in activity. Pro-bombesin(s) probably occur also in the rat and guinea-pig stomach; similarly, a clear-cut heterogeneity is appreciable for the bombesin-like peptide of the human gastric mucosa.

Animals↗
PubMed1978

Actions of peptides isolated from amphibian skin on pancreatic acinar cells.

In dispersed acinar cells prepared from guinea pig pancreas, peptides isolated from amphibian skin (caerulein, bombesin, litorin, and physalaemin) as well as eledoisin, a peptide isolated from the posterior salivary gland of a Mediterranean octopod, increased outflux of 45Ca, release of bound 45Ca, accumulation of cyclic GMP, and release of amylase. In addition, bombesin, litorin, physalaemin, and eledoisin each increased the initial uptake of 45Ca by dispersed acinar cells, whereas C-terminal octapeptide of porcine cholecystokinin (CCK-OP) and carbamylcholine did not increase the initial uptake of 45Ca but, rather, abolished the increase caused by the other agents. None of the actions of these amphibian peptides was altered by concentrations of atropine sufficient to abolish the effects of muscarinic cholinergic agents. None of the amphibian peptides altered cellular cyclic AMP or the increase caused by secretin or porcine vasoactive intestinal peptide (VIP). Acinar cells preincubated with 45Ca plus bombesin showed the same rate of release of 45Ca as did control cells and this rate was not altered by adding bombesin but was increased fivefold by adding CCK-OP. In terms of their chemical structures as well as the potency and efficacy with which they alter acinar cell function, the amphibian peptides plus CCK-OP can be grouped into three pairs: caerulein with CCK-OP, bombesin with litorin, and physalaemin with eledoisin.

Amylases↗
PubMed1977

Amino acid composition and sequence of kassinin, a tachykinin dodecapeptide from the skin of the African frog Kassina senegalensis.

Methanol extracts of the skin of the African amphibian Kassina senegalensis contain a dodecapeptide, kassinin, belonging to the family of tachykinins or physalaemin-like peptides. Kassinin, like all other natural tachykinins, possesses the characteristic C-terminal tripeptide Gly-Leu-Met-NH2 and a phenylalanine residue in position 5 from the C-terminus. However, the amino acid sequence in the N-moiety of the molecule differs sharply from that of the other tachykinins.

Amino Acid Sequence↗
PubMed1975

Uperolein and other active peptides in the skin of the Australian leptodactylid frogs Uperoleia and Taudactylus.

Methanol extracts of the skin of the Australian leptodactylid frogs Uperoleia rugosa, Uperoleia marmorata and Taudactylus acutirostris contain several highly active polypeptides belonging to different peptide families. The most abundant peptide was uperolein, a tachykinin closely related to physalaemin and possessing the same spectrum of biological activity. Uperolein was present in the three species examined. Other tachykinins were represented by Rugosa-uperolein II and Marmorata-uperolein II, the structures of which still await full elucidation. Another peptide family represented in both Uperleia and Taudactylus was that of bombesin-like peptides. They were abundant in Uperoleia rugosa and scarce in Uperoleia marmorata and in Taudactylus. These bombesins are possibly similar to the bombesins, among which is litorin, present in the skin of other Australian leptodactylid frogs. Finally, Taudactylus contained a bradykinin-like peptide and both the Uperoleia species an hitherto unclassified peptide. These new findings have further enriched the already considerable list of active peptides and biogenic amines occurring in the amphibian skin.

Animals↗
PubMed1975

Parallel bioassay of bombesin and litorin, a bombesin-like peptide from the skin of Litoria aurea.

The 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. 2 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 renen-angiotensin system being slight or lacking. 3 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. 4 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. 5 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.

Action Potentials↗
PubMed1974

Gastrin release by bombesin in the dog.

1 The intravenous infusion of bombesin produced in intact dogs and, more strikingly in dogs provided with gastric fistulae a sharp increase in plasma levels of immunoreactive gastrin and at the same time a stimulation of gastric acid secretion. Gastrin response was correlated with the dose of bombesin from approximately 0.1 mug kg(-1) h(-1) (threshold) to 1 mug kg(-1) h(-1) (maximum gastrin release).2 Atropine and metiamide reduced or inhibited gastric acid secretion stimulated by bombesin, but did not affect the rise in gastrin levels.3 Acidification of the whole stomach or of a perfused antral pouch caused a reduced or delayed response to bombesin. However, the inhibitory effect of acidification could be surmounted by prolonging the duration of bombesin infusion.4 Antrectomy greatly reduced the rise in gastrin levels and the increase in acid gastric secretion produced by bombesin, but left unaffected the gastric secretagogue effect of pentagastrin.5 It is concluded that bombesin is a potent releaser of gastrin from the antral mucosa.6 The possible influence of the renal effects evoked by bombesin in the dog on the gastrin response to the polypeptide is discussed.

Animals↗
PubMed1974

Evidence of cholecystokinin release by bombesin in the dog.

1 The intravenous infusion of bombesin elicited in the dog a contraction of the gall bladder with decreased opening pressure of the choledocho-duodenal junction and stimulation of pancreatic secretion.2 The pancreatic juice produced under the influence of bombesin was poor in bicarbonate and rich in protein. Threshold doses of the peptide were of the order of 0.25 mug kg(-1) h(-1) and maximum protein output was obtained with 1 mug kg(-1) h(-1). The pancreatic protein response to bombesin was very similar, in its onset and duration, to that elicited by intraduodenal infusion of L-tryptophan. Infusions of bombesin repeated at short intervals produced tachyphylaxis.3 Antrectomy did not affect the stimulant action of bombesin on the pancreas. Atropine however, reduced the pancreatic protein response to bombesin.4 It is suggested that bombesin acts on the gall bladder and the exocrine pancreas through release of cholecystokinin from the duodenal mucosa. No release of secretion could be demonstrated. It is likely that the releasing activity of bombesin is limited, in the field of gastrointestinal peptides, to those belonging to the gastrin-cholecystokinin family.

Animals↗