Age-related effects of ischemia, lidocaine and verapamil on overdrive-induced suppression of ventricular pacemakers in isolated rat heart.
The effect of age on ventricular automaticity in the isolated perfused rat heart was determined under different conditions. When the ventricle is electrically stimulated at a faster rate, drive cessation is followed by a temporary suppression of ventricular automaticity (overdrive suppression). The effects of ischemia, lidocaine and verapamil on overdrive suppression were studied in isolated perfused adult and senescent rat hearts with complete atrio-ventricular block, by monitoring ventricular escape rate and escape rhythm recovery time after 1 minute of overdrive at a constant multiple (x3) of the spontaneous rate. The results demonstrated that: 1) lidocaine decreases ventricular automaticity especially in senescent hearts; 2) verapamil does not modify ventricular automaticity in basal conditions in either adult or senescent hearts; 3) myocardial ischemia causes a reduction in ventricular automaticity and more markedly in senescent hearts; and 4) lidocaine exaggerates the effect of ischemia, while verapamil seems to antagonize its depressant effect more in adult than in senescent hearts.
Abete
P
P
Institute of Internal Medicine, Cardiology and Cardiovascular Surgery, University of Napoli, Italy.
Ferrara
N
N
Leosco
D
D
Caccese
P
P
Landino
P
P
Sederino
S
S
Balbi
R
R
Rengo
F
F
D000375:Aging / Q000502:physiology*; D000818:Animals; D003327:Coronary Disease / Q000503:physiopathology*; D066298:In Vitro Techniques; D008012:Lidocaine / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D016276:Ventricular Function / Q000187:drug effects*; D014700:Verapamil / Q000494:pharmacology*
D008012:Lidocaine; D014700:Verapamil