AJP - Regulatory, Integrative and Comparative Physiology, Vol 272, Issue 4 1112-R1120, Copyright © 1997 by American Physiological Society

ARTICLES

Cardiovascular effects of homologous bradykinin in rainbow trout

K. R. Olson, D. J. Conklin, L. Weaver Jr, D. W. Duff, C. A. Herman, X. Wang and J. M. Conlon
Indiana University School of Medicine, South Bend Center for Medical Education, 46556, USA.

Bradykinins have only recently been identified in fish, and a detailed analysis of their cardiovascular actions is lacking. The present study examines the cardiovascular effects of trout bradykinin ([Arg0,Trp5,Leu8]bradykinin; tBK) in conscious trout, Oncorhynchus mykiss. tBK (1-10 nmol/kg body wt bolus) produced triphasic pressor-depressor-pressor responses. In phase 1, cardiac output (CO), ventral aortic (P(VA)), dorsal aortic (P(DA)), and central venous pressure increased, whereas systemic (R(S)) and gill resistance (R(G)) were unchanged. In phase 2, R(G) increased, whereas R(S), CO, and heart rate decreased, reducing P(VA) and P(DA). Plasma prostaglandin E2 and the prostacyclin metabolite, 6-ketoprostaglandin F1alpha, were significantly elevated during phase 2, whereas leukotrienes C4 and B4 and thromboxane B2 were unaffected. Phase 3 was produced by an increased CO and R(S) and the return of R(G) to control. Phase 1 pressor response was not blocked by inhibitors of cyclooxygenase, angiotensin-converting enzyme (ACE) or alpha-adrenoceptors (alpha-AD), whereas phase 2 depressor and plasma prostaglandin responses were prevented by cyclooxygenase inhibition. Phase 3 was partially blocked by ACE and alpha-AD inhibitors and is a response to the preceding hypotension. In vitro, tBK only decreased vascular resistance in the perfused splanchnic or skeletal muscle-kidney preparations. These results show that although tBK has multiple effects on the trout cardiovascular system, none of the effects are due to direct tBK stimulation of vascular smooth muscle. Phase 2 vasodilation has features consistent with release of vasodilator prostaglandins while the mechanism of phase 1 constriction is unknown.

This article has been cited by other articles:

				K. R. Olson, M. J. Healy, Z. Qin, N. Skovgaard, B. Vulesevic, D. W. Duff, N. L. Whitfield, G. Yang, R. Wang, and S. F. Perry Hydrogen sulfide as an oxygen sensor in trout gill chemoreceptors Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2008; 295(2): R669 - R680. [Abstract] [Full Text] [PDF]

				D. H. Evans, P. M. Piermarini, and K. P. Choe The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste Physiol Rev, January 1, 2005; 85(1): 97 - 177. [Abstract] [Full Text] [PDF]

				Y. Takei and T. Tsuchida Role of the renin-angiotensin system in drinking of seawater-adapted eels Anguilla japonica: a reevaluation Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2000; 279(3): R1105 - R1111. [Abstract] [Full Text] [PDF]