AJP - Cell Physiology, Vol 252, Issue 6 C670-C676, Copyright © 1987 by American Physiological Society
Beta-adrenergic stimulation of ion transport in primary cultures of avian salt glands
R. J. Lowy and S. A. Ernst
Adrenergic stimulation of transmural ion transport was identified and
characterized in primary cultures of avian salt gland. Adrenergic
activation was mediated by beta-receptors since stimulation of the
short-circuit current (Isc) was blocked by propranolol but not
phentolamine. The Isc's elicited by isoproterenol, epinephrine, and
norepinephrine were dose dependent, with respective EC50 values of 1.5 X
10(-8) M, 5.0 X 10(-6) M, and 1.1 X 10(-5) M. The apparent Ki for
propranolol inhibition after isoproterenol stimulation was 7.5 X 10(-10) M.
8-Br cyclic AMP (8-Br cAMP) and forskolin-elicited Isc's that were
insensitive to propranolol, were potentiated by theophylline, and inhibited
by furosemide or ouabain. Isoproterenol also induced an increase in
ouabain-sensitive respiration in acutely dispersed cells from salt-stressed
juvenile or unstressed adult animals, but not in fully salt-stressed
adults. The data indicate that, in addition to the well-established
cholinergic receptors, beta-adrenergic receptors can control ion transport
in these glands. Furthermore, the results suggest for the first time that
an intracellular effector pathway involving cAMP is present.
