CALCIUM UPTAKE, RELEASE AND Mg-ATPase ACTIVITY OF SARCOPLASMIC RETICULUM FROM ARTERIAL SMOOTH MUSCLE

Mg2+ and Ca2+ Activated ATPase Activities of Bovine Aortic Microsomes

“…1A). This observation is in accord with findings reported from some laboratories (10)(11)(12), but at variance with other reports (6)(7)(8). The reasons for this disparity are not clear.…”

“…This activity is analagous to the classic "extra" ATPase activity of striated muscle sarcoplasmic reticulum ( 1,9). However, several investigators could not detect "extra" ATPase in smooth muscle microsomes even when accumulation of calcium was demonstrable (10)(11)(12).…”

Mobilization of Cellular Calcium and Contraction-Relaxation of Vascular Smooth Muscle

“…It has been established that the activity of the contractile system in smooth Ca is utilized for the activation of contractile proteins,since smooth muscle can contract upon certain stimulus in Ca2+ free medium,as shown in this experiment and others (VAN BREEMEN et al,1973,BOSE andINNES,1975). Several workers have morphologically and biochemically proved the existence of Ca binding site(s)in smooth muscle cell,such as the internal surface of the cell membrane (PoPEscu et al,1974;DEBBAS et al,1975;ATSUMI and SUGI,1976)and the sarcoplasmic reticulum and mitochondria (SOMLYO et al,1977;MCGUFFEE and BAGBY,1976).Isolated cell membrane and sarcoplasmic reticulum from varieties of smooth muscle exhibit Ca accumulating ability in the presence of ATP and Mg2+(FITZPATRIC et al,1972;HURWITZ et al,1973;YAMASHITA et al,1976;WEI et al,1976).…”