Control Of Contractile Function Research Articles

Donald Bers.

Donald Bers.

An analytical approach to the preparation and characterization of subcellular membranes from canine mesenteric arteries.

Subcellular membrane fractions were isolated from dog mesenteric arteries by differential and isopynic sucrose density gradient centrifugations. Isolated membrane fractions were characterized by marker enzyme activities, morphological features and sodium dodecyl sulfate-polyacrylamide gel electrophoretic patterns. Our results show that the microsomal fraction isolated by conventional differential centrifugation was highly heterogenous and contained substantial amount of plasma membranes which could be further enriched as a light density membrane fraction on a discontinuous sucrose density gradient. The microsomal fraction and its subfractions were vesicular in appearance under electron microscope and were capable of binding and actively transporting Ca2+. The binding of Ca2+ and ATP-supported Ca2+-transport in the presence or absence of oxalate paralleled the distribution of plasma membrane marker enzyme activities suggesting that plasma membranes in vascular smooth muscle may play a major role in handling Ca2+ and thus the control of contractile function.

Control of contraction of vascular muscle: relation to hypertension

Ca2+ plays a vital role in the control of contractile function of vascular smooth muscle. A change in Ca2+-handling by vascular muscle may explain some altered functions associated with hypertension. This article summarizes the methodologies and their limitations in the studies of how Ca2+ is made available and then removed in the excitation-contraction-relaxation processes. A direct approach using isolated subcellular membranes in the studies of Ca2+-binding and transmembrane movement is described along with insights derived from it into the pathophysiological mechanisms of hypertension.