Aging and digitalis sensitivity of cardiac muscle in rats.

摘要: Abstract The cause of the reduced tolerance aged rats to arrhythmogenic effect ouabain was studied in left atrial and ventricular muscle preparations obtained from 3-, 8- or 26-month old Fischer 344 rats. Under 1.5-Hz stimulation, concentration-response curves for positive inotropic showed a tendency shift with age. toxic effects occured at lower digoxin concentrations senescent especially when stimulated higher frequency (4 Hz), although differences were not apparent 1.5 Hz. No age-related difference intracellular sodium potassium concentration observed perfused paced There no significant age on Na + -induced activation ,K -ATPase. In myocardium, however, upstroke velocity action potential under high stimulations, ability follow stimulation compromised. These results suggest that reserve capacity pump is muscle, thereby elevating its sensitivity cardiac glycoside.