Calcium Movements in Muscle

Calcium Movements in Muscle

The movements of calcium in muscle have been followed during contraction and contracture to test the hypothesis that the release of calcium from the surface of the muscle membrane during stimulation initiates the contractile mechanism. Nitrate ion increases the calcium influx during a single twitch and during potassium contracture, and also increases the tension developed. The increased entry o...

Calcium movements, distribution, and functions in smooth muscle.

Calcium movements during contraction in molluscan smooth muscle, and the loci of calcium binding and release.

1. Conventional **Ca efflux studies of Buccinum and Neptunia pharangeal retractor and columella muscles revealed the presence of a fast and a slow calcium compartment. KCl-induced depolarization caused a stimulation of the *Ca efflux from the slow compartment, suggesting that this compartment may be related to calcium diffusion from intracellular sources. 2. Fine structural studies showed a lac...

Ca2+ movements in smooth muscle.

We describe the Ca2+ movements in smooth muscle cells at rest and during activation and relaxation as deduced from transplasmalemmal Ca2+ fluxes and contractile respnses. The general picture which emerges is: the resting cell has a [Ca2+]cyt below 10(-7) M and large gradients are poised across both the cell membrane and intracellular membranes. Excitation opens up Ca2+ channels which are linked...

Excess membrane cholesterol alters calcium movements, cytosolic calcium levels, and membrane fluidity in arterial smooth muscle cells.

The relations between membrane cholesterol content, basal (unstimulated) transmembrane 45Ca2+ movements, cytosolic calcium levels, and membrane fluidity were investigated in cultured rabbit aortic smooth muscle cells (SMCs) and isolated SMC plasma membrane microsomes. SMCs were enriched with unesterified (free) cholesterol (FC) for 18-24 hours with medium containing human low density lipoprotei...