The role of @entity460 current and changes in intracellular @entity460 concentration ([ @entity141 ]i) in regulation of @entity2045 ( @entity2045 ) during electrical restitution process was studied in @entity1 ventricular preparations. Properly timed action potentials were recorded from multicellular preparations and isolated cardiomyocytes using conventional microelectrodes and @entity4527 -containing patch pipettes. @entity2045 increased monotonically in @entity235 and @entity840 ventricular preparations with increasing diastolic interval (DI), while in @entity95 papillary muscles the restitution process was biphasic: @entity2045 first lengthened, then shortened as the DI increased. When the restitution process was studied in single cardiomyocytes using @entity4527 -containing patch pipettes, the restitution pattern was similar in the three species studied. Similarly, no difference was observed in the recovery time constant of @entity460 current (/Ca-L) measured under these conditions in voltage clamped myocytes. Loading the myocytes with the [ @entity141 ]i-chelator @entity11008 had adverse effects in @entity95 and @entity235 cells. In @entity95 myocytes steady-state @entity2045 lengthened and the late shortening component of restitution was abolished in BAPTA-loaded cells. In @entity235 myocytes BAPTA-load shortened steady-state @entity2045 markedly, and during restitution, @entity2045 decreased with increasing DI. The late shortening component of restitution, observed in untreated @entity95 preparations, was greatly reduced after @entity594 treatment, but remained preserved in the presence of @entity973 or @entity7976 . Beat to beat changes in @entity2045 , peak/Ca-L and [ @entity141 ]i, measured using the fluorescent dye, @entity593 , were monitored in @entity95 ventricular myocytes after a 1-min period of rest. In these cells, the shortening of @entity2045 was accompanied by a gradual reduction of the peak/Ca-L and elevation of diastolic [ @entity141 ]i during the initial eight post-rest action potentials. It is concluded that elevation of [ @entity141 ]i shortens, while reduction of [ @entity141 ]i lengthens @entity2045 in @entity95 , but not in @entity235 ventricular myocytes. These differences may probably be related to different distributions of [ @entity141 ]i-dependent ion currents and/or to differences in @entity460 handling between the two species.

Intracellular @entity460 and electrical restitution in XXXX cardiac cells.

@entity1 :: ('9606', 'Species') :: ['mammalian'] @entity2045 :: ('MESH:D009207', 'Disease') :: ['APD', 'action potential duration'] @entity235 :: ('9615', 'Species') :: ['canine'] @entity4527 :: ('MESH:D004533', 'Chemical') :: ['EGTA'] @entity840 :: ('10141', 'Species') :: ['guinea pig'] @entity95 :: ('9986', 'Species') :: ['rabbit'] @entity973 :: ('MESH:D015761', 'Chemical') :: ['4-aminopyridine'] @entity593 :: ('MESH:D016257', 'Chemical') :: ['Fura-2'] @entity460 :: ('MESH:D002118', 'Chemical') :: ['calcium'] @entity594 :: ('MESH:D009543', 'Chemical') :: ['nifedipine'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca2+'] @entity11008 :: ('MESH:C070379', 'Chemical') :: ['BAPTA-AM'] @entity7976 :: ('MESH:D020108', 'Chemical') :: ['nicorandil']
@entity1 :: (9606,Species) :: ['mammalian']
