Comparison of ionic effects on longitudinal and circular muscle of cat jejunum

Nitric Oxide-mediated Relaxation by High K+in Human Gastric Longitudinal Smooth Muscle

“…In this study, however, we observed unexpected high K + -induced relaxation in longitudinal muscle of corpus and higher portion of corpus from GC side. Relaxation of longitudinal smooth muscle in contrast to circular muscle might be produced in various reasons; 1) the dissociation of motility and regulation of [Ca 2+ ] i 2) different properties of the muscle fibers 3) different spontaneous activity in each muscle [14,16]. As described in the result, high K + -induced relaxation of corpus was not affected by pretreatment of NBC (p>0.05).…”

“…This dissociation could be interpreted in a harmonious way that when Ca 2+ influxes into muscle cell by high K + stimulation circular muscles contract and longitudinal muscles relax. To date, the mechanism underlying each muscle layer's different activities is unclear: marked differences of intracellular Ca 2+ ([Ca 2+ ] i ) regulation by K + -depolarization [14-16]. Dissociative patterns of motility between circular and longitudinal muscle might came not only from the neural activity but also from the different properties of the muscles [14].…”

High K+-Induced Relaxation by Nitric Oxide in Human Gastric Fundus

“…Stimulation with high K + concentrations resulted in contraction of circular muscles but relaxation of longitudinal muscles. The mechanism underlying the responses of each muscle layer seems very complicated, indicating different regulation of intracellular Ca 2+ ([Ca 2+ ] i ) by K + -stimulation and/or regional differences in electrical characteristics of each type of gastric muscle [12,22,23]. Dissociation of motility between both muscles might come from different characteristics of the muscles and/or neural responses [12].…”

The abundance of Aplysia gliagrana depends on Ca2+ and/or Na+ concentrations in sea water

“…In marine molluscs such as Aplysia the hemolymph has a high sodium content, close to that of sea water, and it is obvious that the neurons do not need a glial Nat store, especially at the level of the neuronal cell body or a t the nerve terminals, where the action potential (at least partly) depends on an inward Ca2+ current. Even with as much as 10 mM Ca2+ in the milieu, a calcium store may counter the antagonistic effect of Na' on Ca2+ fluxes that has been observed in several physiological mechanisms: the [Ca2+]JNat]E ratio was shown to be critical in cardiac muscle contraction (Luttgau and Niedergerke, 19581, in smooth muscle spike amplitude (Connor and Prosser, 1974), and in neurotransmitter secretion (Blaszkowski and Bogdanski, 1971;Dreifuss et al, 1971). The hypothesis that calcium-containing membrane-bound glial granules could function as a Ca2+ store to regulate the perineuronal spaces has been proposed for molluscs (Nicaise, 1973) and also vertebrates (Gambetti et al, 19751, with little experimental evidence in either case.…”