J. Biol. Chem., Vol. 261, Issue 13, 5745-5750, May, 1986
Control of stimulus-secretion coupling in adrenal medullary chromaffin cells by microfilament-specific macromolecules
JE Friedman, PI Lelkes, K Rosenheck and A Oplatka
We have incorporated the myosin fragment heavy meromyosin (HMM), which is
known to interact mechanochemically and enzymatically with actin filaments,
into intact chromaffin cells of the bovine adrenal medulla, in order to
study the possible involvement of actin and myosin in stimulus-secretion
coupling. HMM was found to stimulate secretion of catecholamines, to cause
depolarization of the plasma membrane, and to enhance 22Na+ uptake.
HMM-stimulated catecholamine secretion was dependent on the presence of
extracellular Na+. The Na+ uptake caused by HMM was inhibited by 10 microM
amiloride. Acetylcholine-stimulated catecholamine secretion and 22Na+
uptake were both enhanced by HMM incorporation. A Na+/H+ antiporter,
activated by the interaction of HMM with the cells' microfilaments, seems
to be involved in HMM action and could possibly also be a component of
stimulus-secretion coupling in chromaffin cells, induced by regular
agonists.