F. Perez-villa et al., Effect of cyclooxygenase inhibition on the adaptation of coronary blood flow to tachycardia, REV ESP CAR, 53(1), 2000, pp. 59-65
Background. The role of different endothelium-derived vasoactive substances
in the regulation of coronary circulation during tachycardia is not well d
efined. In order to elucidate the contribution of prostacyclin to the adapt
ation of coronary blood flow to tachycardia, the effect of meclofenamate, a
cyclooxygenase inhibitor on the coronary blood flow response to rapid atri
al pacing was analyzed in a porcine model.
Methods. A group of seventeen pigs were instrumented for coronary blood flo
w, 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, befor
e and after saline serum (n = 6), meclofenamate 5 mg/kg, i.v. (n = 7) or me
clofenamate 35 mgikg, i.v. (n = 4).
Results. Neither saline nor meclofenamate modified the normal increase of c
oronary blood flow provoked by rapid atrial pacing (163 +/- 28% increase be
fore versus 172 +/- 29% after saline; 159 +/- 21% increase before versus 16
1 +/- 22% after meclofenamate low dosis and 201 +/- 39% before vs 172 +/- 3
6 after meclofenamate high dosis). There were no differences in the respons
e of coronary vascular resistance to tachycardia before and after meclofena
mate (44% reduction vs 40% respectively).
Conclusion. Cyclooxygenase blockade does not modify the response of coronar
y circulation to rapid atrial pacing, suggesting that prostacyclin does not
play a limiting role in the regulation of coronary blood flow during tachy
cardia in this model.