Calcium channels in vitamin B6 deficiency-induced hypertension.

Objective: To compare the acute hypotensive effects of various calcium channel modulators in vitamin B6-deficient hypertensive (B6DHT) rats.

Methods: Adult male Sprague-Dawley rats were fed a vitamin B6-deficient diet for 7-10 weeks, during which systolic blood pressure (SBP) was measured in the B6DHT and control rats, using tail-cuff plethysmography. The effects of the calcium antagonists nifedipine, verapamil, diltiazem and (-)-202-791 on SBP were determined in conscious B6DHT rats. The effect of the calcium agonist BAY K 8644 on the SBP of rats fed various levels of pyridoxine was also determined.

Results: All of the calcium antagonists used were effective in lowering the SBP of the B6DHT rats with the rank order of potency: nifedipine > (-)-202-791 > (+/-)-verapamil > diltiazem. BAY K 8644 elevated the SBP of older rats fed a normal commercially available diet, but had no effect when the vitamin B6 content of their diet was increased or removed for a short period.

Conclusion: Calcium channel function appears to be related to vitamin B6 status in the rat.