Effect of Human Blood Serum on M-Cholinoreactivity of Rat Stomach Smooth Muscles

摘要

Earlier, we put forward a hypothesis that humanblood contains a system of endogenous direct-actionchemoreactivity modulators that selectively increasethe efficiency of activation of cell receptors (endogenous sensitizers) or, conversely, decrease it (endogenous blockers). In particular, experiments on longitudinal strips of uterine horns of nonpregnant rats,which exhibited high M-cholinoreactivity, showedthat human blood serum at certain dilutions (1 :500, 1 : 100, 1 : 50) decreases the stimulatory effectof acetylcholine (10~(-6) g/ml) [6, 9]. On the basis ofthese data, it was assumed that an M-cholinergic receptor endogenous blocker is present in blood. Earlier,M-cholinolytic activity of low dilutions (1 : 5 to 1 : 40)of frog, rat, and rabbit blood sera was demonstrated inexperiments on isolated frog and rabbit hearts in thelaboratory of T.M. Turpaev [5]. Later, this phenomenonwas demonstrated in our laboratory in studies of humanblood serum in experiments on isolated frog heart [10].The naturp and physiological role of the endogenousblocker of M-cholinergic receptors remain obscure.The most probable candidate for the major componentof the endogenous blocker of M-cholinergic receptorsis lysophosphatidylcholine, which, similarly to bloodserum, attenuates the effects of ACh on frog and rabbithearts [5].