Generation of vasoactive substances in trout and rat plasma by trypsin and kallikrein

D. W. Lipke, K. D. Meisheri, K. R. Olson

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

In the preceding study we demonstrated kallikrein-like enzymatic activity in trout tissues and showed that kallikrein incubated with trout plasma (T60K) produces a vasopressor substance(s). The present study further examines the effects of T60K in fish and mammals in vitro and in vivo. T60K produced a dose-dependent pressor response in both trout and rats, whereas kallikrein-activated rat plasma (R60K) was pressor in trout and depressor in rats. Captopril did not affect the response of rats to T60K or R60K. Phenoxybenzamine attenuated the T60K response in trout but not in rats, thus T60K effects in trout are partially mediated through catecholamines. Blockade of angiotensin II (ANG II) receptors in rats with [Sar1,Ala8]ANG II abolished the pressor effects of T60K. T60K produced dose-dependent contractions in isolated trout and rabbit arteries; ANG II was ineffective in trout arteries. T60K-contracted trout arteries were relaxed by atrial natriuretic peptide and forskolin, whereas diltiazem and sodium nitroprusside were without effect. [Sar1,Ala8]ANG II inhibited T60K-induced contractions of rabbit arteries and relaxed rings previously contracted with T60K. The active component of T60K has a molecular weight <10,000, is heat stable, and is inactivated by peptidases. It is immunologically different than mammalian angiotensins but binds to and displaces radiolabeled ANG II from ANG II receptors. These results suggest that kallikrein forms a vasoactive substance(s) in trout plasma that is neither bradykinin nor ANG II but is similar to the latter in its pharmacological effects.

Original languageEnglish (US)
Pages (from-to)R507-R514
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume258
Issue number2 27-2
DOIs
StatePublished - 1990

Keywords

  • angiotensin antagonist
  • angiotensin receptors
  • blood pressure
  • glandular kallikrein

ASJC Scopus subject areas

  • Physiology

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