Dissociation of subsarcolemmal from global cytosolic [Ca2+] in myocytes from guinea‐pig coronary artery.

Abstract

Changes in cytosolic

Ca2+ images and K+ current during depolarization in smooth muscle cells of the guinea‐pig vas deferens and urinary bladder

“…10, DSR) in this type of smooth muscle cell. The discrepancy that IK,Ca activation upon depolarization is faster than the rise of [Ca¥] monitored by Ca¥ indicators over the whole (or a substantial part) of the cell area (Stehno-Bittle & Sturek, 1992;Ganitkevich & Isenberg, 1996;Imaizumi et al 1996a) is completely resolved by this study. In this study, the rise of [Ca¥] in superficial hot spots during depolarization occurred with the same time course as the activation of IK,Ca (Fig.…”

Elementary and global aspects of calcium signalling.

“…The elementary events outlined in Fig. 3 (Ganitkevich & Isenberg, 1996). Evidence that such elementary events can contribute to the resting level of calcium has also been obtained in HeLa cells and in Xenopus oocytes (Parker & Yao, 1996;Parker, Choi & Yao, 1996a from 100 nM up to about 200 FM (Llina's, Sugimori & Silver, 1992;Sugimori, Lang, Silver & Llina's, 1994).…”

“…Subsarcolemmal calcium sparks stimulate localized potassium channels (Fig. 4B) to give STOCs which can be dissociated from the global elevation of calcium (Stehno-Bittel & Sturek, 1992;Ganitkevich & Isenberg, 1996). Indeed, the STOCs in arterial smooth muscle may perform a specific function by stimulating the efflux of potassium; the STOCs hyperpolarize the membrane thus leading to relaxation (Nelson et al 1995).…”

Regulation of Calcium Sparks and Spontaneous Transient Outward Currents by RyR3 in Arterial Vascular Smooth Muscle Cells

“…We used ryanodine and caffeine to further elucidate the role of internal Ca 2ϩ stores in STOC generation in our cell preparations. 29,30 Ryanodine caused a decrease in STOCs firing frequency in both Ϫ/Ϫ RyR3 and ϩ/ϩ RyR3 cells. 6,10,24 Caffeine led to a temporary arrest in STOCs in our cells.…”