Role of Na+/K+ ATPase on the Relaxation of Rabbit Ear and Femoral Arteries

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Abstract
The role of Na+/K+ ATPase in vascular relaxation has been studied by determining its inhibitory effects on 2-mm segments from rabbit central ear and femoral arteries, mounted for isometric tension recording. Acetylcholine (10-8-10-4 M), the nitric oxide donor sodium nitroprusside (10-8-3 × 10-4 M), the potassium channel agonist cromakalim (10-8-3 × 10-5 M), histamine (10-8-10-4 M) in the presence of the H1 antagonist chlorpheniramine (10-5 M), and papaverine (10-6-3 × 10-4 M) all produced arterial relaxation in ear and femoral arteries precontracted with endothelin 1. Addition of potassium (6 × 10-3- 1.2 × 10-2 M) caused relaxation of the same arteries preincubated in potassium-free medium. Ouabain (10-5 M) an inhibitor of Na+/K+ ATPase, reduced the relaxation of ear arteries, but not of femoral arteries, in response to acetylcholine; it also reduced the response to sodium nitroprusside, cromakalim or histamine, and abolished the relaxation to potassium, but did not modify the response to papaverine, in both types of artery. These results suggest that Na+/K+ ATPase might play a role in the relaxation of ear and femoral arteries to nitrovasodilators, to potassium channel openers and to activation of histamine receptors, and that Na+/K+ ATPase might play a role in the cholinergic relaxation of ear, but not femoral arteries, suggesting that the mechanism of cholinergic relaxation might differ in each type of artery.
Funding Information
  • FIS ((Nos 92/289 and 93/338))
  • CICYT ((Nos 91 /0020 and 93/0085))
  • CAM ((157/94).)

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