Effect of Dietary Chromium on Resistance Artery Function and Nitric Oxide Signaling in the Sucrose-Fed Spontaneously Hypertensive Rat

Abstract

Background: Consumption of high-glycemic index foods contributes to the development of hypertension in some patients. Likewise, in spontaneously hypertensive rats (SHR), high sucrose promotes a secondary rise in systolic blood pressure (SBP). Chromium (III) (Cr³⁺) prevents sucrose-induced hypertension, but leaves the basal hypertension that characterizes SHR intact. Methods: Since hypertension entails increased peripheral resistance, we compared effects of Cr³⁺ on resistance arteries from SHR fed low-glycemic (starch) versus high-glycemic (sucrose) index diets. Subgroups of SHR also received Cr³⁺. Structure, stiffness, and vasodilation of mesenteric resistance arteries were studied using pressurized myography. Results: Sucrose increased SBP in SHR and, exclusively in sucrose-fed SHR, Cr³⁺ reduced SBP and augmented acetylcholine or nitroprusside-dependent vasodilation. Neither sucrose nor Cr³⁺ affected artery structure or stiffness. Since Cr³⁺ enhanced vasodilation, we assessed endothelial NO synthase (eNOS), guanylate cyclase, cGMP-dependent protein kinase (PKG-1α and 1β), and PKG activity by immunoblotting. Sucrose reduced eNOS, PKG-1β, and PKG activity. Cr³⁺ prevented the effects of sucrose on NO signaling. Conclusion: In hypertension exacerbated by high-glycemic index diet, Cr³⁺ reduces SBP. The BP-lowering effect of Cr³⁺, selectively on sucrose-induced but not basal hypertension in SHR, involves at least in part, improving vasodilatory function vis-à-vis restoration of NO signaling in resistance arteries.

Blood pressure lowering effects of niacin-bound chromium(III) (NBC) in sucrose-fed rats: Renin–angiotensin system

“…This suggests that the NO system was more active in the NBC group. Accordingly, this supports the contention that a relatively depressed NO system is involved in sugar-induced hypertension [5] and that NBC can affect this system as well as the RAS.…”

“…Kopilas et al [5] examined sugar-induced hypertension and concluded that the NO system was significantly involved in the pathogenesis. We examined the ability of LNAME, a substance that can inhibit the dilatory actions of NO, to influence SBP and found a trend to raise the blood pressure, more so in the NBC group.…”

“…The exact pathological mechanism(s) behind sugar-induced hypertension are uncertain, but the elevated SBP may relate to a number of perturbed underlying regulating mechanisms including augmented catecholamine levels [4], disturbed vasodilatory function via disturbances in NO signaling in blood vessels [5], alterations in fluid and electrolyte balance [6], and disturbances in the renin-angiotensin system (RAS) manifested by elevated circulating levels of angiotensin-2 [7]. The latter is particularly interesting because of recent findings.…”

Effects of chromium picolinate on vascular reactivity and cardiac ischemia-reperfusion injury in spontaneously hypertensive rats

“…While Cr(pic)3 has been extensively investigated in relation to carbohydrate metabolism, there are only a few studies devoted to its effects on the cardiovascular system [14, 17, 19, 24–27, 29]. The consideration of the cardiovascular effects of the supplement becomes more relevant in view of the documented association between type 2 diabetes/glucose intolerance and cardiovascular disorders such as abnormal vascular function, increased blood pressure and augmented susceptibility to ischemic heart disease [3, 4, 11, 28].…”

Comparing metabolic effects of six different commercial trivalent chromium compounds

“…Laboratory and clinical studies indicate that certain forms of trivalent chromium have the capability to: (a) increase fat loss while preserving muscle [9,10]; (b) overcome insulin resistance and ameliorate diabetes [5,8]; (c) suppress free radical formation [11]; (d) lower total cholesterol and low-density lipoprotein (LDL) [12]; (e) decrease systolic blood pressure (SBP) [11,13]; (f) influence fluid and electrolyte balance [13]; (g) alter catecholamine metabolism [14] and (h) influence nitric oxide (NO) functions [15]. Finally, a recent report also suggests that trivalent chromium may increase useful lifespan, at least in rodents [16].…”