Conflicting data on the inotropic effect of insulin are present in the literature suggesting a positive inotropic property or no inotropic effect or even a negative influence. To clarify the reason for these diverging findings, dose-response curves of insulin have been performed in isolated working @entity35 and @entity840 hearts perfused with Krebs-Henseleit buffer containing 0.9, 1.25, 2.5, and 5 mM @entity141 at 37 degrees C. At 1.25 mM [ @entity141 ], insulin (8 to 16 IU) regularly improved the inotropic state. LVdP/dt(max) increased significantly from 1,900 to 2,300 mm Hg/s (+21 %) in @entity840 hearts and from 3,197 to 4,345 mm Hg/s (+36 %) in @entity35 hearts. LVEDP did not change significantly. Myocardial @entity26 consumption increased parallel with contractility. Heart rate was not influenced in either species. Coronary flow increased by 16.5 % in @entity840 hearts, but decreased in @entity35 hearts by 13.6 % (p < 0.05 each). With 0.9 mM [ @entity141 ] the positive inotropic effect of insulin did not further augment. At 2.5 mM [ @entity141 ] insulin exhibited in both species no significant change of LVdP/dt(max) but very high insulin doses depressed the heart. At 5 mM [ @entity141 ] insulin depressed the heart significantly already at lower concentrations. At 31 degrees C and 1.25 mM [ @entity141 ] the positive inotropic insulin effect was preserved. We conclude that the positive inotropic insulin effect in @entity35 and @entity840 hearts depends on the extracellular [ @entity141 ], i.e., is maximal around 1.25 mM [ @entity141 ] and is reduced or absent at higher [ @entity141 ] or may even become negative.

Influence of perfusate calcium concentration on the inotropic insulin effect in isolated XXXX and @entity35 hearts.

@entity35 :: ('10116', 'Species') :: ['rat'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca(2+)'] @entity840 :: ('10141', 'Species') :: ['guinea pig'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen']
@entity840 :: (10141,Species) :: ['guinea pig']
