ABSTRACT
Chronic experiments on dogs with gastric fistulas were carried out to study the influence of angiotensin 1 and angiotensin 2 on pentagastrin- and histamine-induced gastric acid secretion. It was established that both angiotensins inhibited gastric acid secretion stimulated by pentagastrin but not by histamine. Comparative analysis of the effects of stimulation and inhibition of cholino- and adrenoreceptors on this inhibitory action of angiotensins suggested the mediation of angiotensin influence through the modulation of cholinergic reactions of parietal cells in the stomach.
Subject(s)
Angiotensin II/pharmacology , Angiotensin I/pharmacology , Gastric Mucosa/drug effects , Gastric Mucosa/metabolism , Analysis of Variance , Animals , Depression, Chemical , Dogs , Drug Interactions , Gastric Acid/metabolism , Gastric Juice/drug effects , Gastric Juice/metabolism , Parietal Cells, Gastric/drug effects , Parietal Cells, Gastric/metabolism , Stimulation, ChemicalABSTRACT
The surface activity of angiotensin-2 was studied using the method of dynamical capacitor and Wilgelmi. Angiotensin was shown to possess the surface activity, forming well regulated insoluble monolayers of liquid-gas interfaces with peptide adsorption of 3.7 x 10(-6) M/sm2 and area of 0.45 nm2 per one molecule. It is assumed that due to these properties angiotensin-2 under physiological conditions can interact with molecules of the lipid matrix of biological membranes.
Subject(s)
Angiotensin II/metabolism , Adsorption , Hydrogen-Ion Concentration , In Vitro Techniques , Membrane Lipids/metabolism , Surface PropertiesABSTRACT
The studies of lipid monolayers showed the interaction of an angiotensin-2 and lipid monolayers to be a two-stage process. In the first stage peptide molecules were adsorbed due to electrical interaction in the plane of polar heads of lipid molecules. In the second stage peptide molecules incorporated into the lipid matrix owing to hydrophobic interactions. These results suggest that the lipid matrix may perform the function of a catalyst of the peptide-receptor interaction by changing the spatial structure of angiotensin molecules at the transition of the latter from hydrophobic environment.
Subject(s)
Angiotensin II/metabolism , Membrane Lipids/metabolism , Drug Interactions , In Vitro Techniques , Lipoproteins/metabolism , Protein Binding , Structure-Activity Relationship , Time FactorsABSTRACT
The authors studied the interaction of bradykinin and aminoacids which are in its molecule composition with lipid monolayers. It is supposed that the primary process of bradykinin bounding with plasmatic membrane of the effector cells is the peptide interaction with membrane lipid matrix.
