- Title
- Coronary haemodynamic effect of nifedipine (Bay a 1040) and glyceryl trinitrate in unanaesthetized dogs
- Creator
- White, Saxon William; Porges, W. L.; McRitchie, R. J.
- Relation
- Clinical and Experimental Pharmacology and Physiology Vol. 1, Issue 1, p. 77-86
- Publisher Link
- http://dx.doi.org/10.1111/j.1440-1681.1974.tb00529.x
- Publisher
- Wiley-Blackwell Publishing Asia
- Resource Type
- journal article
- Date
- 1974
- Description
- SUMMARY 1. The effects on the coronary circulation of intravenous injections of nifedipine were compared with those of glyceryl trinitrate in conscious dogs using chronically implanted Doppler flow probes. 2. Each drug causes a fall in arterial pressure and a rise in heart rate, circumflex flow and circumflex conductance. 3. Dose-response curves for peak changes in these variables are quantitatively similar for each drug (six dogs); threshold effects occur with about 0.25 μg/kg, and maximal effects with about 16 μg/kg. However, the change in circumflex conductance induced by 8 μg/kg of nifedipine last on the average of 3.5 min, whereas the effects of circumflex conductance induced by the same dose of glyceryl trinitrate last 1 min. 4. The effects of 8 μg/kg of each drug were investigated in 5 dogs treated with propranolol, and propranolol plus atropine. The findings suggest that the rise in heart rate elicited by both drugs is mediated entirely through autonomic mechanisms, whereas 80% of the increase in conductance elicited by both drugs is due to their direct vasodilator action and 20% is attributable to autonomic mechanisms. 5. The administration of nifedipine into the buccal cavity in doses suggested for clinical use rapidly induces a fall in arterial pressure and a rise in heart rate, coronary flow, cardiac output and cardiac work; these effects may persist for longer than 1 h. 6. It is concluded that nifedipine is a potent, long acting coronary and systemic vasodilator in the unanaesthetized dog. It appears to have haemodynamic effects which resemble those of glyceryl trinitrate in some respects but not in others.
- Subject
- coronary circulation; glyceryl trinitrate; nifedipine; vasodilator agents
- Identifier
- http://hdl.handle.net/1959.13/938713
- Identifier
- uon:12657
- Identifier
- ISSN:0305-1870
- Language
- eng
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