Premium
The effect of hormones and peptides involved in water balance on rat colonic motility in vitro
Author(s) -
VODERHOLZER W. A.,
ALLESCHER H.D.,
MÜLLERLISSNER S. A.
Publication year - 1995
Publication title -
neurogastroenterology and motility
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.489
H-Index - 105
eISSN - 1365-2982
pISSN - 1350-1925
DOI - 10.1111/j.1365-2982.1995.tb00204.x
Subject(s) - medicine , endocrinology , aldosterone , stimulation , angiotensin ii , vasopressin , hormone , motility , carbachol , chemistry , basal (medicine) , peptide hormone , renin–angiotensin system , biology , blood pressure , insulin , genetics
We have previously shown that restriction of water intake decreased stool frequency and stool weight in volunteers. The aim of this study was to investigate whether these effects of thirst could be mediated by an action of systematically released hormones on colonic smooth muscle. Using isolated colonic smooth muscle strips the effect of arginine‐vasopressin (AVP), angiotensin II (ANG II) and aldosterone on rat colonic motility in vitro was investigated. AVP (10 −12 ‐10 −10 mol/***1) and aldosterone (3 times 10 −10 ‐3 times 10 −8 mol/1) and physiological hormonal concentrations of ANG II (10 −13 ‐10 −10 mol/***1) had no effect on either basal activity, direct stimulation of colonic smooth muscle or neurally stimulated contractions using carbachol 10 −7 ‐3 times 10 −5 mol/***1 or neurally stimulated contractions using electrical field stimulation at various stimulation frequencies (1–10 pps, 1 ms, 40 V). ANG II in higher concentrations (10 −7 ‐10 −6 mol/***1) increased basal activity and neurally mediated contractions. Accordingly, ANG II (10 −6 mol/***1) caused a prestimulation but did not increase the maximum contractile effect of carbachol. The response to ANG II was not affected by atropine (10 −6 mol/1). TTX (10 −6 mol/1) and N‐nitro‐L8‐arginine (L‐NNA) (3 times 10 −4 mol/1) stimulated basal muscular activity but did not affect the maximum contractile effect of ANG II. Systemic serum concentrations of AVP, aldosterone and ANG II are presumably not involved in thirst‐induced colonic motility changes. The ANG II effect in higher concentrations is mediated by a direct stimulatory smooth muscle effect and/or by facilitating neuronal liberation of acetylcholine. These higher concentrations of ANG II could be reached when ANG II is acting as a neurotransmitter or through a local renin‐angiotensin system.