Effects of fluvastatin on endothelium-derived hyperpolarizing factor- and nitric oxide-mediated relaxations in arteries of hypertensive rats.
Endothelial cells release endothelium-derived hyperpolarizing factor (EDHF), as well as nitric oxide (NO). It has recently been suggested that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) improve NO-mediated endothelial function, partially independently of their cholesterol-lowering effects. It is, however, unclear whether statins improve EDHF-mediated responses. Eight-month-old stroke-prone spontaneously hypertensive rats (SHRSP) were treated with fluvastatin (10 mg/kg per day) for 1 month. Age-matched, normotensive Wistar Kyoto (WKY) rats served as controls. Both EDHF- and NO-mediated relaxations were impaired in SHRSP compared with WKY rats. Fluvastatin treatment did not affect blood pressure and serum total cholesterol. The acetylcholine (ACh)-induced, EDHF-mediated hyperpolarization in mesenteric arteries did not significantly differ between fluvastatin-treated SHRSP and untreated SHRSP and the responses in both groups were significantly smaller compared with those of WKY rats. Endothelium-derived hyperpolarizing factor-mediated relaxations, as assessed by the relaxation to ACh in mesenteric arteries contracted with noradrenaline in the presence of N(G)-nitro-l-arginine and indomethacin, were virtually absent and similar in both SHRSP groups. In contrast, NO-mediated relaxation, as assessed by the relaxation in response to ACh in rings contracted with 77 mmol/L KCl, was improved in fluvastatin-treated SHRSP compared with untreated SHRSP (maximum relaxation in control and fluvastatin groups 42.0 +/- 5.2 and 61.2 +/- 3.8%, respectively; P < 0.05). Hyperpolarization and relaxation in response to levcromakalim, an ATP-sensitive K(+) channel opener, were similar between the two SHRSP groups. These findings suggest that fluvastatin improves NO-mediated relaxation, but not EDHF-mediated hyperpolarization and relaxation, in SHRSP. Thus, the beneficial effects of the statin on endothelial function may be mainly ascribed to an improvement in the NO pathway, but not EDHF.
Kansui
Yasuo
Y
Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Fujii
Koji
K
Goto
Kenichi
K
Abe
Isao
I
Iida
Mitsuo
M
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001685:Biological Factors / Q000502:physiology*; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology* / Q000627:therapeutic use; D000077340:Fluvastatin; D006973:Hypertension / Q000188:drug therapy* / Q000378:metabolism; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D009569:Nitric Oxide / Q000502:physiology*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology
D001685:Biological Factors; D005229:Fatty Acids, Monounsaturated; D007211:Indoles; C067410:endothelium-dependent hyperpolarization factor; D009569:Nitric Oxide; D000077340:Fluvastatin; D000109:Acetylcholine