Theophylline affects the inotropic status of guinea-pig left atria by actions on the sarcolemma and sarcoplasmic reticulum.
Theophylline (0.1, 0.3 mM) produced a positive inotropism which was maximum by 15 min but was partially or completely absent by 45 min. The mechanism for this response was investigated using post-rest potentiation and positive staircase, phenomenon associated with the sarcoplasmic reticulum and sarcolemma, respectively. Staircase was enhanced at 15 min, but not after 45 min. Post-rest potentiation was attenuated by theophylline. The data suggest that theophylline's effect on cardiac contractility results from opposing actions on the sarcolemma and sarcoplasmic reticulum.
Zavecz
J H
JH
Department of Pharmacology, Louisiana State University School of Medicine, Shreveport 71130-3932.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D012508:Sarcolemma / Q000187:drug effects*; D012519:Sarcoplasmic Reticulum / Q000187:drug effects*; D013806:Theophylline / Q000494:pharmacology*
D013806:Theophylline; D002118:Calcium