AJP - Regulatory, Integrative and Comparative Physiology, Vol 273, Issue 1 49-R57, Copyright © 1997 by American Physiological Society

ARTICLES

Angiotensins stimulate catecholamine release from the chromaffin tissue of the rainbow trout

N. J. Bernier and S. F. Perry
Department of Biology, University of Ottawa, Ontario, Canada.

Immunohistochemical and pharmacological techniques were utilized to investigate the relationships between angiotensins and catecholamine release from the chromaffin tissue of rainbow trout (Oncorhynchus mykiss). Double labeling with [Asp1, Ile5]angiotensin II-fluorescein isothiocyanate (ANG II-FITC) and anti-dopamine beta-hydroxylase revealed specific ANG II binding sites on chromaffin cells. Injection (1 nmol/kg body wt) of either ANG II-FITC, [Asn1, Val5, Asn9]ANG I, [Asp1, Ile5, His9]ANG I, [Asn1, Val5]ANG II, [Asp1, Val5]ANG II, or [Asp1, Ile5]ANG II elicited catecholamine release from in situ perfusion preparations of the head kidney. Catecholamine release elicited by [Asn1, Val5]ANG II (10(-13) to 10(-7) mol/kg body wt) was dose dependent, and the secretion of epinephrine (Epi) was greater than that of norepinephrine (NE). Relative to the results obtained with the [Asn1, Val5]ANG II treatment (1 nmol/kg body wt), Epi release was 72 and 82% lower in response to injections (1 nmol/kg body wt) of [Asn1, Val5]ANG I [amino acid (AA) positions 1-7] and [Asn1, Val5]ANG I (AA 1-6), respectively. Pretreatment with either losartan (10(-5) M), PD-123319 (10(-5) M), or hexamethonium (10(-3) M) had no effect on [Asn1, Val5]ANG II-elicited catecholamine release. Pretreatment with captopril (10(-4) M) significantly reduced [Asn1, Val5, Asn9]ANG I-elicited Epi and NE release and decreased basal catecholamine release. These results provide direct evidence that angiotensins can elicit catecholamine release from the chromaffin tissue via specific ANG II binding sites and indicate that the synthesis of ANG II may be either local or systemic.

This article has been cited by other articles:

				K. N. Lapner and S. F. Perry The role of angiotensin II in regulating catecholamine secretion during hypoxia in rainbow trout Oncorhynchus mykiss J. Exp. Biol., January 12, 2001; 204(23): 4169 - 4176. [Abstract] [Full Text] [PDF]

				J. A. Brown, R. K. Paley, S. Amer, and S. J. Aves Evidence for an intrarenal renin-angiotensin system in the rainbow trout, Oncorhynchus mykiss Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2000; 278(6): R1685 - R1691. [Abstract] [Full Text] [PDF]