The effect of stimulus interval variation on action potential repolarization of atrial muscle preparations in normotensive (NWR) and spontaneously hypertensive rats (SHR).
Action potential (AP) repolarization was tested in atrial preparations of adult NWR and SHR. Prolongation of pause interval interposed in the basic driving frequency of 2 Hz caused a shortening of the early phase and a prolongation of the final phase of repolarization in both NWR and SHR. AP's in SHR exhibited longer durations compared to NWR. However, at pause prolongation the relative increment of AP-duration at the 70% repolarization level (APD70) was less in SHR. This might indicate a positive correlation between electrical and mechanical restitution kinetics. The Na-Ca-exchange could be a possible link for an interpretation of this correlation.
D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000502:physiology; D004558:Electric Stimulation; D006325:Heart Atria / Q000503:physiopathology*; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009200:Myocardial Contraction; D051381:Rats; D011918:Rats, Inbred SHR / Q000502:physiology; D012964:Sodium / Q000502:physiology
D012964:Sodium; D002118:Calcium