Simultaneous blockade of the cyclooxygenase and L-arginine-nitric oxide pathways prevents the antiarrhythmic effects of classical preconditioning (part 5)

classical preconditioning (part 5)

Group 1 (controls): Sixteen animals served as controls and were allowed to stabilize after surgery for 1 h. Twenty minutes before LAD occlusion, saline (0.5 mL/min) was infused into a small branch of the LAD proximal to the occlusion site, then the LAD was occluded for 25 mins followed by reperfusion.
Group 2 (preconditioned): Twenty-two animals were preconditioned as previously described by occluding the LAD for two 5 min periods, with a 20 min reperfusion period in between. Twenty minutes later the artery was reoccluded for 25 mins, after which the ischemic area was reperfused. Group 3 (meclofenamate plus L-NAME plus preconditioned): Nine dogs were given sodium meclofenamate (2 mg/kg intravenously) 30 mins before, and L-NAME (5 mg/kg, by slow local intracoronary injection) 20 mins before, the first preconditioning occlusion. This was to determine whether nitric oxide and prostaglandins are generated during the preconditioning procedure, and hence whether they are important trigger substances for preconditioning. The dogs were then preconditioned as described above. In this group, seven of the nine dogs died during the preconditioning procedure; only the two surviving dogs were then subjected to the long occlusion.

Group 4 (preconditioned plus meclofenamate plus L-NAME): Ten dogs were preconditioned in the same manner as the group 2 dogs but, 5 mins after the second preconditioning occlusion (ie, 15 mins before the prolonged [25 min] occlusion), sodium meclofenamate and, 5 mins later (ie, 10 mins before the 25 min occlusion), L-NAME were given by the same routes and in the same doses as described for the group 3 dogs. This was to determine whether inhibition of both the L-arginine-nitric oxide and the cyclooxygenase pathways after the preconditioning stimulus modifies the antiar-rhythmic effects of preconditioning; that is, whether the generation of nitric oxide and prostaglandins is also important in mediating protection during the prolonged ischemic episode. You always want to be sure that drug works for you and still does not cost too much? Then you should definitely shop with my canadian pharmacy always getting the exact quality you wanted for less money than anywhere else.

Category: Cardiology

Tags: Cyclooxygenase pathway, Ischemic preconditioning, L-arginine-nitric oxide pathway

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