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.
Ramon R. Gonzalez, Jr.
David A. Hessinger
Marvin A. Peters
Master of Science (MS)
Year Degree Awarded
Date (Title Page)
Library of Congress/MESH Subject Headings
Venoms; Diltiazem; Dantrolene; Atenolol.
Loma Linda University Libraries
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.
Bonlie, Wayne R., "Effects of Portuguese Man-of-War (PHYSALIA PHYSALIS) Venom on Isolated Rabbit Atria" (1993). Loma Linda University Electronic Theses, Dissertations & Projects. 831.
Loma Linda University Electronic Theses and Dissertations
Loma Linda University. Del E. Webb Memorial Library. University Archives