Tetrahydrobiopterin (BH4) coinfusion significantly augmented endothelium-dependent vasodilation in hypertensive patients, increasing forearm blood flow from 14.8 to 25.6 mL/min/100 mL tissue (P<.05).
Case-Control (n=16)
Does tetrahydrobiopterin (BH4) supplementation improve endothelium-dependent vasodilation in patients with essential hypertension and normotensive individuals?
Tetrahydrobiopterin supplementation acutely improves endothelium-dependent vasodilation in both hypertensive and normotensive individuals, highlighting its mechanistic role in endothelial function.
Absolute Event Rate: 25.6% vs 14.8%
p-value: p=<.05
BACKGROUND: A deficiency of tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide (NO) synthase, decreases NO synthesis and increases superoxide production. Supplementation of BH4 has been postulated to improve endothelial function in atherosclerotic patients. The purpose of this study was to determine whether BH4 restores endothelium-dependent vasodilation in patients with essential hypertension. METHODS: We evaluated the effects of BH4 on forearm vascular responses to acetylcholine (ACh), an endothelium-dependent vasodilator, and isosorbide dinitrate (ISDN), an endothelium-independent vasodilator, both in patients with essential hypertension and in age- and sex-matched normal control subjects. Forearm blood flow (FBF) was measured using strain gauge plethysmography. RESULTS: The response of FBF to ACh was less in hypertensive patients (n = 8) than in normal control subjects (n = 8). There was no significant difference in FBF response to ISDN in the two groups. During coinfusion of BH4 (500 mg/min), the FBF response to ACh in hypertensive patients increased significantly (14.8 +/- 4.6 to 25.6 +/- 7.3 mL/min/100 mL tissue, P < .05) to the level of normal control subjects. In the control subjects, also, BH4 augmented the FBF response to ACh (27.8 +/- 8.7 to 36.1 +/- 9.6 mL/min/100 mL tissue, P < .05). The increase in FBF after ISDN was not altered by BH4 in either group (each group, n = 6). CONCLUSION: Supplementation of BH4 augments endothelium-dependent vasodilation in both normotensive and hypertensive individuals.
Higashi et al. (Mon,) conducted a case-control in Essential hypertension (n=16). Tetrahydrobiopterin (BH4) vs. Baseline (pre-infusion) and normal control subjects was evaluated on Forearm blood flow response to acetylcholine (p=<.05). Tetrahydrobiopterin (BH4) coinfusion significantly augmented endothelium-dependent vasodilation in hypertensive patients, increasing forearm blood flow from 14.8 to 25.6 mL/min/100 mL tissue (P<.05).