Acetylcholine responses are impaired in patients with pathophysiologic levels of plasma triglycerides but normal plasma levels of LDL cholesterol. The impairment observed was comparable to that obtained in hypercholesterolemic patients. We conclude that impaired responses to acetylcholine normally associated with hypercholesterolemia also occur in hypertriglyceridemia. These findings identify a potential mechanism by which high plasma triglyceride levels may be atherogenic independent of LDL cholesterol levels.

Abstract-The objective of this study was to investigate the effects of cycle training on basal nitric oxide (NO) production and endothelium-dependent dilator capacity in hypercholesterolemic patients in whom acetylcholine responsiveness is impaired. Nine sedentary hypercholesterolemic volunteers (total plasma cholesterol Ͼ6.0 mmol/L; 2 female) aged 44Ϯ3 years (meanϮSEM) participated in the study. Subjects remained sedentary for 4 weeks and performed 4 weeks of home-based cycle training (3ϫ30 minutes/week at 65% maximum oxygen consumption [VO 2 max]) in a randomized order. Arteriovenous nitrate/nitrite (NO x ) gradient was assessed and plethysmography was used to measure the forearm blood flow responses to arterial infusions of acetylcholine, sodium nitroprusside, and N G mono methyl L-arginine. Training increased VO 2 max from 30.4Ϯ1.9 to 34.3Ϯ1.4 mL ⅐ kg Ϫ1 ⅐ min Ϫ1 (Pϭ0.01). Intrabrachial diastolic blood pressure was reduced from 70Ϯ3 to 68Ϯ3 mm Hg (Pϭ0.02) with training, whereas systolic pressure did not change. Plasma triglycerides and total, LDL, and HDL cholesterol were not different between interventions. In the sedentary state, there was a positive forearm arteriovenous difference in plasma NO x indicating net extraction (6.8Ϯ4.0 nmol ⅐ 100 mL Ϫ1 ⅐ min Ϫ1 ), whereas in the trained state this difference was negative, indicating net production (Ϫ5.8Ϯ5.8 nmol ⅐ 100 mL Key Words: exercise Ⅲ endothelium-dependent vasodilation Ⅲ acetylcholine Ⅲ lipids Ⅲ hyperlipidemia N itric oxide (NO) has received much recent attention as one potential mediator of some of the vascular benefits derived from regular exercise. 1 A number of studies in both animals and humans have recognized that endothelially derived NO plays a role in blood flow regulation during acute, dynamic exercise. 2 In particular, it has been postulated that vasodilatation in active muscle promotes a pressure gradient and thus increased blood flow that stimulates NO production from upstream arteries. 3 NO mediated dilation of "feed" arteries can therefore permit increased microvascular flow without reduction in muscle perfusion pressure. With regular exercise it appears that there are adaptations in this system that may be partly responsible for the reduction in cardiovascular risk associated with the trained state.Studies in rats and rabbits have provided evidence for enhanced aortic endothelial dependent vasodilatation and basal release of NO with exercise training. 4 -8 Importantly, similar improvements in response to training have been observed in the coronary vasculature of pigs and dogs. 9 -14 All training related studies of endothelial function in humans have been carried out in peripheral vessels. Our laboratory has shown that 4 weeks of cycle training increases basal production of NO from the forearm. 15 In this study, forearm blood flow and blood viscosity were elevated by 230% and 16%, respectively, immediately after a single 30-minute bout of exercise, and 60 minutes after cessation of exercise, forearm blood flow remained elevated by 75%. W...

1 Legume-derived iso¯avones such as genistein, diadzein and equol have been associated with a reduction in risk of cardiovascular disease. In the current study, we explore the vascular activity of several iso¯avone metabolites namely dihydrodaidzein, cis and trans-tetrahydrodaidzein and dehydroequol for potential cardioprotective properties. 2 Rat isolated aortic rings were used. 17b-oestradiol, equol, and all four of the metabolites studied signi®cantly antagonized contractile responses to noradrenaline. 3 The direct vasodilatory action of these compounds were examined and in contrast to 17b-oestradiol, the vasodilatory eect of which was demonstrated to be endothelium independent, the dilatory action of all four compounds could be inhibited by endothelium denudation. 4 Further, the dilatory action of both dihydrodaidzein and cis-tetrahydrodaidzein were inhibited by the nitric oxide synthase inhibitor, N o -nitro-L-arginine (NOLA), by the soluble guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and by 40 mM KCl. Dilatory responses to dehydroequol and trans-tetrahydrodaidzein, on the other hand, were inhibited by 40 mM KCL but not by NOLA nor ODQ. 5 Finally, we examined the protective potential of these compounds in inhibiting endothelium damage by oxidized low density lipoprotein (ox-LDL). Trans-tetrahydrodaidzein was at least 10 fold more potent than 17b-oestradiol in protecting against ox-LDL induced damage. 6 We conclude that the iso¯avone metabolites, dihydrodaidzein, cis-and trans-tetrahydrodaidzein and dehydroequol, may potentially represent a novel series of cardioprotective therapeutics.

Endogenous ETs act at ET(A)-receptors to reduce MBF and CBF, but ET(B)-receptors have little direct role in physiological control of renal haemodynamics. Bolus doses of ET-1 act at ET(B)-receptors in the kidney to increase MBF. The effects of bolus ET-1 on the cortical vasculature appear to result from the competing influences of ET(A)-mediated vasoconstriction and ET(B)-mediated vasodilatation.