title: The effect of stimulus interval variation on action potential repolarization of atrial muscle preparations in normotensive (NWR) and spontaneously hypertensive rats (SHR).
abstract: 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.
mesh_terms: 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
chemical_list: D012964:Sodium; D002118:Calcium