Antihypertensive effect of sialoadenectomy in one-kidney, one clip hypertension in the rat

We have examined the effect of removal of the submandibular gland on one-kidney, one clip (1K1C) hypertension in the rat. Five weeks after application of a silver clip with a 0.20-mm gap, 15 hypertensive rats were sialoadenectomized. This was followed by a decrease in systolic blood pressure (SBP) within 1 day by 22 +/- 4 mmHg (+/- s.e.m.) and in nine rats pressure stabilized within 1 week at 133 +/- 5 (cf. 166 +/- 2 before sialoadenectomy). In the other six rats the initial hypotensive response was followed by a gradual return to hypertensive levels, reaching 178 +/- 4 mmHg 6 weeks later. Sham-sialoadenectomized rats remained hypertensive throughout. When a 0.15-mm gap clip was used in a similar experiment rats became hypertensive after 2 weeks, and sialoadenectomy lowered SBP to normal in half of them, after which pressure tended to return to hypertensive levels in most. No change in SBP was found in sham-operated hypertensive rats. Sialoadenectomy performed at the time of clipping with a 0.15-mm gap clip and unilateral nephrectomy delayed the development of hypertension. Systolic pressure then fell from 153 +/- 14 at 4 weeks to 105 +/- 8 at 12 weeks after operation in five rats, but continued to increase in eight rats from 148 +/- 10 at 4 weeks to 172 +/- 15 at 12 weeks. These experiments thus demonstrate that the submandibular gland may contribute to the onset and maintenance of one-kidney, one clip hypertension in the rat, particularly in less severe stenosis.