Potassium preserves endothelial function and enhances aortic compliance in Dahl rats.
It has recently been proposed that in rat models of genetic hypertension, supplemental dietary potassium preserves release of endothelium-derived relaxing factor independently of its capacity to either attenuate hypertension or increase plasma potassium. To test this hypothesis in Dahl salt-sensitive rats given sodium chloride (4%) for 3 weeks, we supplemented dietary potassium (2.1%) with either KCl (n = 16) or KHCO3 (n = 16). Compared with unsupplemented rats (n = 16), rats supplemented with either potassium salt had a lower mean arterial pressure and a greater release of endothelium-derived relaxing factor, as assessed from acetylcholine-induced relaxation of precontracted aortic rings. However, the maximum relaxation response to acetylcholine correlated inversely with blood pressure (r = -.82, P < .001), not only in the KCl (r = -.68, P < .002) and KHCO3 (r = -.77, P < .001) groups but also in unsupplemented rats (r = -.86, P < .001). With potassium supplementation, plasma potassium concentrations measured between 4 and 6 PM did not increase, but those measured between 4 and 6 AM did increase (P < .05). In isolated ring segments, aortic compliance was greater in both the KCl and KHCO3 groups than in unsupplemented rats (0.015 and 0.017 vs 0.009 mm2/mm Hg) (P < .01). This greater compliance could not be related to differences in blood pressure, plasma potassium, or collagen or elastin content of the aortic wall.(ABSTRACT TRUNCATED AT 250 WORDS)
Sudhir
K
K
Department of Medicine, University of California, San Francisco 94143-0126.
Kurtz
T W
TW
Yock
P G
PG
Connolly
A J
AJ
Morris
R C
RC
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D003187:Compliance / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced / Q000188:drug therapy; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D011188:Potassium / Q000097:blood / Q000652:urine; D011189:Potassium Chloride / Q000494:pharmacology*; D017680:Potassium Compounds; D017419:Potassium, Dietary / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology
D001639:Bicarbonates; D017680:Potassium Compounds; D017419:Potassium, Dietary; D009569:Nitric Oxide; D011189:Potassium Chloride; C026329:potassium bicarbonate; D000109:Acetylcholine; D011188:Potassium