Effects of Some Vasoactive Neuropeptides on Motor Activity of Smooth Muscle Organ´s Strips from Different Areas of Gastrointestinal System

1 Trakia University, Department of Physiology, Pathophysiology and Pharmacology, Medical Faculty,BG – 6000 Stara Zagora, Bulgaria
2 Bulgarian Academy of Sciences, Institute of Neurobiology, BG - 1113 Sofia, Bulgaria


ILIEVA, G., A. TOLEKOVA, R. KALFIN, P. HADZHIBOZHEVA and Ts. GEORGIEV, 2014. Effects of some vasoactive neuropeptides on motor activity of smooth muscle organ´s strips from different areas of gastrointestinal system. Bulg. J. Agric. Sci., 20: 220-226


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.

Key words: smooth muscle strips, organ baths, angiotensin II, vasopressin
Abbreviations: ACE – Angiotensin-converting enzyme; Ang II – Angiotensin II; AUC – Area under the curve; AV P – Arginine-vasopressin; DA G – Diacylglycerol; GIT – Gastro-intestinal tract; IP3 – Inositol triphosphate; RAS – Renin-angiotensin system; SMC – Smooth muscle contractions

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