Abstract
Myocytes were isolated from neonatal rat hearts and grown in tissue-culture dishes for 1–2 days. Spontaneously formed cell pairs were used to study the conductance of gap junctions. The experiments involved a double voltage-clamp approach and whole-cell, tight-seal recording. Exposure to arachidonic acid (AA) produced a quasi dose-dependent decrease in junctional conductance, g j (binding constant, K d=4 μM; Hill coefficient, n = 0.75). AA-dependent uncoupling was reversible. Addition of 1 mg/ml albumin to the bath solution accelerated the recovery. During control, cell pairs exhibited a gradual decrease in g j (16.4 % in 6 min). Exposure to 20 μM 4-bromophenacyl bromide, a phospholipase inhibitor, suppressed the decay in g j (1.8% in 6 min), suggesting that endogenous AA may be involved in spontaneous uncoupling. The effect of AA on g j was specific. Arachidic acid (100 μM) and arachidonamide (10 μM), structural analogues of AA, had no effect on g j. Currents recorded shortly before complete uncoupling caused by AA, or early during recovery from uncoupling, revealed random opening and closing of single channels. The single channel conductance, γ j, was not affected by the concentration of AA (1 μM–100 μM). The mean γ j turned out to be 33.5 pS. The results suggest that AA-dependent uncoupling was caused via decrease in open channel probability, presumably mediated by a direct action on channel proteins.
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Fluri, G.S., Rüdisüli, A., Willi, M. et al. Effects of arachidonic acid on the gap junctions of neonatal rat heart cells. Pflugers Arch. 417, 149–156 (1990). https://doi.org/10.1007/BF00370692
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DOI: https://doi.org/10.1007/BF00370692