AJP - Regulatory, Integrative and Comparative Physiology, Vol 259, Issue 5 921-R924, Copyright © 1990 by American Physiological Society
Catecholamines depress endolymphatic sac direct current potential in guinea pigs
N. Mori, N. Uozumi and S. Sakai
Department of Otolaryngology, Kagawa Medical School, Japan.
To test the possibility that catecholamines have an influence on the
function of the endolymphatic sac (ES), which is known to absorb the
endolymph, the effect of catecholamines on the ES direct current potential
(ESP) was examined in the guinea pig. The ESP was recorded extradurally by
the posterior occipital approach. Isoproterenol (Iso), epinephrine (Epi),
and norepinephrine (NE) were administered intravenously for 4 min using an
infusion pump. Catecholamines reversibly depressed the ESP with the rank
order of potency Iso greater than Epi greater than NE. The threshold doses
were 0.021, 0.27, and 1.94 micrograms/kg for Iso, Epi, and NE,
respectively. beta-Antagonist (propranolol) blocked the action of
catecholamines on the ESP but alpha-antagonist (phentolamine) did not. This
indicates that beta-adrenergic action induces the ESP change. This study
implies that catecholamines may regulate the function of the ES.
