Abstract

The cardiac effects of Portuguese man-of-war venom were studied using isolated atria from rabbits. Venom added (7.1 µg protein/ml) to the bath solution stimulates heart rate 120% (P < 0.01) and increases contraction amplitude 308% (P < 0.001). Both effects are dependent on bath concentrations of venom and calcium. The increase in contraction amplitude is significantly attenuated by diltiazem (0.8 µM) and atenolol (10 µM). Atenolol, a β1-adrenergic antagonist, completely blocks the increase in heart rate. Dantrolene (10 µM) did not significantly block the venom's effects. Ryanodine binding increases in the presence of venom showing that the venom is not in competition for calcium channels on the sarcoplasmic reticulum. These results suggest that the venom acts on the sarcolemma to increase calcium permeability, thereby causing an increase in contraction amplitude and possibly causing β1-adrenergic stimulation.

LLU Discipline

Physiology

Department

Physiology

School

Graduate School

First Advisor

Ramon R. Gonzalez, Jr.

Second Advisor

David A. Hessinger

Third Advisor

Marvin A. Peters

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1993

Date (Title Page)

8-1993

Language

English

Library of Congress/MESH Subject Headings

Venoms; Diltiazem; Dantrolene; Atenolol.

Type

Thesis

Page Count

v; 23

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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