[Effect of cyclooxygenase inhibition on the adaptation of coronary blood flow to tachycardia].
BACKGROUND
The role of different endothelium-derived vasoactive substances in the regulation of coronary circulation during tachycardia is not well defined. In order to elucidate the contribution of prostacyclin to the adaptation of coronary blood flow to tachycardia, the effect of meclofenamate, a cyclooxygenase inhibitor on the coronary blood flow response to rapid atrial pacing was analyzed in a porcine model.


METHODS
A group of seventeen pigs were instrumented for coronary blood flow, aortic pressure and atrial pacing. Heart rate was increased by 20 beats every 5 minutes. Coronary blood flow and aortic pressure were measured, and coronary resistance calculated, basally and at each pacing interval, before and after saline serum (n = 6), meclofenamate 5 mg/kg, i.v. (n = 7) or meclofenamate 35 mg/kg, i.v. (n = 4).


RESULTS
Neither saline nor meclofenamate modified the normal increase of coronary blood flow provoked by rapid atrial pacing (163 +/- 28% increase before versus 172 +/- 29% after saline; 159 +/- 21% increase before versus 161 +/- 22% after meclofenamate low doses and 201 +/- 39% before vs 172 +/- 36 after meclofenamate high doses). There were no differences in the response of coronary vascular resistance to tachycardia before and after meclofenamate (44% reduction vs 40% respectively).


CONCLUSIONS
Cyclooxygenase blockade does not modify the response of coronary circulation to rapid atrial pacing, suggesting that prostacyclin does not play a limiting role in the regulation of coronary blood flow during tachycardia in this model.
Pérez-Villa
F
F
Instituto de Enfermedades Cardiovasculares, Hospital Clínic, Barcelona.
Epelde
F
F
Roig
E
E
Heras
M
M
Rigol
M
M
Díez-Aja
S
S
Zurbano
M J
MJ
Escolar
G
G
Sanz
G
G
D000818:Animals; D002304:Cardiac Pacing, Artificial; D003326:Coronary Circulation / Q000187:drug effects*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D011464:Epoprostenol / Q000502:physiology*; D005260:Female; D006339:Heart Rate; D008297:Male; D008469:Meclofenamic Acid / Q000494:pharmacology*; D011448:Prostaglandin Antagonists / Q000494:pharmacology*; D013552:Swine; D013610:Tachycardia / Q000188:drug therapy / Q000503:physiopathology*
D016861:Cyclooxygenase Inhibitors; D011448:Prostaglandin Antagonists; D008469:Meclofenamic Acid; D011464:Epoprostenol