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The effects of timolol on arrhythmias and prostanoid release during canine myocardial ischaemia and reperfusion
Author(s) -
Coker Susan J.,
Parratt James R.
Publication year - 1984
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1984.tb16134.x
Subject(s) - timolol , medicine , anesthesia , cardiology , heart rate , hemodynamics , blood pressure , chloralose , ischemia , ventricular fibrillation , vascular resistance , intraocular pressure , surgery
1 Timolol (50 μg kg −1 ), administered intravenously to chloralose‐anaesthetized open‐chest greyhounds 30 min prior to occlusion of the left anterior descending coronary artery, reduced heart rate and mean arterial blood pressure. This dose caused a 20 fold increase in the dose of isoprenaline required to increase heart rate by 25 beats min −1 . 2 During the first 30 min of myocardial ischaemia the number of extrasystoles in the timolol‐treated dogs (327 ± 179) was less than in the control group (888 ± 168) and none of the dogs that received timolol fibrillated. 3 The haemodynamic changes induced by coronary artery occlusion (decreased cardiac output and stroke volume, increased peripheral vascular resistance) were similar in both control and timolol‐treated dogs as were the increases in P co 2 and decreases in P O 2 and pH in blood draining from the ischaemic myocardium. 4 Timolol did not alter the release during myocardial ischaemia, of either thromboxane B 2 or prostacyclin (measured as 6‐keto PGF 1α ). 5 Reperfusion‐induced venticular fibrillation occurred in 7 out of 8 control dogs and in 5 out of 10 timolol‐treated dogs. The overall survival following occlusion and reperfusion was improved by 10% to 50% by timolol.