In this study the influence of myocardial ischemia on intramural carbon dioxide tension (PmCO2) was measured directly with the mass spectrometer in open-chest, anesthetized dogs with repetitive 10 minute coronary artery occlusions separated by 45 minutes of reflow. During each occlusion regional myocardial blood flow was measured by the Xenon washout technique. In all dogs, the rise in PmCO2 (ΔPmCO2) with the first artery occlusion was consistently greater than with the second occlusion. Subsequently, in the dogs not receiving an intervention (controls), ΔPmCO2 with the third occlusion was unchanged from the second occlusion. When propranolol, hyaluronidase, or nitroglycerin were administered individually prior to the third occlusion, ΔPmCO2 fell significantly from its value during the (control) second occlusion, and the combination of the three caused an even more marked decline in ΔPmCO2. In contrast, isoproterenol infused during the third occlusion caused ΔPmCO2 to rise significantly. Blood flow to the ischemic area increased with hyaluronidase and was unchanged in the other groups. Therefore, (1) the mass spectrometric measurement of PmCO2 can be used to assess the efficacy of interventions to limit ischemic injury; (2) propranolol, hyaluronidase, and nitroglycerin given alone reduce the rise in PmCO2 whereas isoproterenol increases it; and (3) the combination of propranolol, hyaluronidase, and nitroglycerin exerts a markedly beneficial effect on myocardial ischemic injury, as reflected by a drastic diminution in the rise of PmCO2.
|Original language||English (US)|
|Number of pages||9|
|Journal||Transactions of the Association of American Physicians|
|State||Published - Jan 1 1978|
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