AJP - Endocrinology and Metabolism, Vol 242, Issue 3 137-E145, Copyright © 1982 by American Physiological Society
Ionomycin stimulates secretion of catecholamines from cat adrenal gland and spleen
M. H. Carvalho, J. C. Prat, A. G. Garcia and S. M. Kirpekar
Ionomycin, a polyether antibiotic, stimulated the secretion of
catecholamines and dopamine beta-hydroxylase from perfused adrenal glands
and [3H]norepinephrine ([3H]NE) from spleens of the cat. Release was
calcium dependent, and strontium or barium did not substitute for calcium.
Ionomycin failed to release [3H]NE from reserpinized spleens. High
magnesium did not interfere in the ionomycin response, but lanthanum and
manganese blocked it. Ionomycin response that was pH dependent was not
affected by potassium depolarization. The secretory response to ionomycin
was enhanced when both glycolysis and oxidative metabolism were inhibited.
It is concluded that ionomycin introduces calcium into the chromaffin cells
and adrenergic nerve terminals to cause the secretory response and that a
rise in intracellular calcium may be an adequate stimulus for secretion.
