Inter-species variations in myocardial responsiveness to cardiac glycosides: possible relations to the thyroid status

Journal of Molecular and Cellular Cardiology
B FelzenO Binah

Abstract

Mammalian species differ in their myocardial responsiveness to cardiac glycosides; whereas glycosides induce a marked positive inotropic effect in species such as dog, rabbit and guinea-pig, the rat myocardium is virtually insensitive. We investigated the physiological basis for this phenomenon by testing the hypothesis that the inter-species variations in the response of the myocardium to cardiac glycosides results, at least in part, from species-related differences in the "thyroid status". In the present study we focused on the toxic effects of the glycosides, and studied ouabain-induced delayed afterdepolarizations (DAD): (1) in guinea-pigs, rats and mice, which encompass a wide range of thyroid statuses, as indicated by their O2 consumption and thyroid hormone levels; (2) in guinea-pigs and rats in which the thyroid status was decreased by propylthiouracil treatment or increased by thyroxine administration (in the former species only). DAD were readily induced in guinea-pigs after 40 to 60 min superfusion with 10(-6) M ouabain and 5.4 mM Ca2+. In rats, DAD were induced only when the Ca2+ concentration was raised to 8.1 mM, but were absent in mice even after 2 h of superfusion with ouabain and 8.1 mM Ca2+. In guinea-pigs and...Continue Reading

Citations

Jun 18, 2005·Journal of Pharmacological and Toxicological Methods·Daniela S HauserGuido Hanauer
Feb 15, 1992·American Journal of Medical Genetics·P BeightonP Tsipouras

Related Concepts

Nerve Impulses
Metazoa
Drug Resistance
Cavia porcellus
Heart
Mouse, Inbred ICRC
Ouabain
Oxygen Consumption
Propylthiouracil
August Rats

Related Feeds

Cardiomyopathy

Cardiomyopathy is a disease of the heart muscle, that can lead to muscular or electrical dysfunction of the heart. It is often an irreversible disease that is associated with a poor prognosis. There are different causes and classifications of cardiomyopathies. Here are the latest discoveries pertaining to this disease.

Cardiac Glycosides

Cardiac glycosides are a diverse family of naturally derived compounds that bind to and inhibit na+/k+-atpase. Discover the latest research on cardiac glycosides heres.