Participation of bivalent ions in the acetylcholine-provoked gastric smooth-muscle phasis contractions.

Experiments were carried out on muscle strips from cat antrum. Acetylcholine added to Ca++ -free medium containing EDTA (10-5M) exerted no effect on the phasic contractions of the gastric smooth muscle. Ba++at low concentrations (0,1 to 0,5mM) replaced Ca++with respect to the acetylcholine effect. On the background of blocked cholinergic (atropine 10-5M) and adrenergic (phentolamine 10-5 M and propranolol 10-5M) structures Ba++ provoked slow potentials and cotractions with a frequency of 9 to 10 cpm. delta600 (10-5M) blocked the Ba++-induced myogenic electrical and contractile activities of the smooth muscle. The role of the cholinergic structures for synchronizing the electrical and contractile activities of the smooth muscle is considered.