@entity63 and @entity519 both cause a rapid loss of @entity972 from myocardial cells. We have investigated the relationship between the accumulation of @entity972 in the extracellular fluid and the early loss of contractility. Experiments were performed on the isolated @entity95 heart perfused with physiological saline at 36 degrees C, paced at 3 Hz. Tension was recorded from the apex. Extracellular @entity972 concentration [( K+]o) was recorded with small ion-selective electrodes. After the onset of global @entity63 , [K+]o rose within 15 sec and reached 9.5 +/- 1.1 mmoles/liter after 5 min. Developed @entity2701 ( @entity2701 ) fell to 9 +/- 2% of control over the same period. During substrate-free @entity519 , @entity2701 declined at a similar rate, and [K+]o rose slowly to 5.5 +/- 0.1 mmoles/liter after 5 min. The relationship between [K]o and @entity2701 during normal perfusion and oxygenation was investigated by incrementally increasing the perfusate [K+]. @entity2701 dropped to 78.6 +/- 4.5% of control at a [K+]o of 9 mmoles/liter. Comparison of the relationship between [K+]o and @entity2701 during high- @entity972 perfusion, @entity63 , and @entity519 shows that extracellular @entity972 accumulation per se makes almost no contribution to the decline of contractile function in @entity63 or @entity519 . (Values are means +/- S.E., N = 5.)

Absence of a relationship between extracellular @entity972 accumulation and contractile failure in the @entity63 or @entity519 XXXX heart.

@entity63 :: ('MESH:D007511', 'Disease') :: ['Ischemia', 'ischemia'] @entity95 :: ('9986', 'Species') :: ['rabbit'] @entity519 :: ('MESH:D000860', 'Disease') :: ['hypoxia'] @entity972 :: ('MESH:D011188', 'Chemical') :: ['potassium'] @entity2701 :: ('MESH:D018781', 'Disease') :: ['tension', 'T']
@entity95 :: (9986,Species) :: ['rabbit']
