EFFECTS OF SOME VASOACTIVE NEUROPEPTIDES ON MOTOR ACTIVITY OF SMOOTH MUSCLE ORGANS STRIPS FROM DIFFERENT AREAS OF GASTROINTESTINAL SYSTEM

Ts. Georgiev, R. Kalfin, G. Ilieva, P. Hadzhibozheva, A. Tolekova

Abstract: The aim of this study was to analyze in detail and to compare the effects of Angiotensin II (Ang II) and Arginine - vasopressin (AV P) on the contractile activity of smooth muscle strips from different rat gastrointestinal segments by application of time-parameter analysis. Longitudinal muscle strips from the rat stomach and intestine were used for in vitro recording of contraction, iduced by Ang II (10-6 M) and AV P (10-6 M). Amplitude, area under the curve (AUC) and time-parameters of the curves force-vs.-time of the contraction were determined. The colon and rectum responded to Ang II with more powerful contractions (3.43 ± 0.56 g and 4.74 ± 0.65 g, respectively). Jejunum and colon from one side and stomach, duodenum and rectum on other hand showed a similar pattern of contractions and relaxations. The response of the ileum was different. It was shown bilateral symmetry in the responses of the gastrointestinal tract. The differences in the responses of smooth muscle strips on Ang II in the various segments are probably due to unequal distribution of the density and opposite effects of AT1 and AT2- receptors, the presence of local RAS and аctivation of various transduction pathways. AVP induced tonic contractions of the preparations from the stomach. In the intestines, AV P was ineffective.

Keywords: angiotensin II; organ baths; smooth muscle strips; vasopressin

Date published: 2017-10-17