Apocynin Ameliorates Cadmium-Induced Hypertension Through Elevation of Endothelium Nitric Oxide Synthase

Apocynin is reported to have antioxidant and NADPH oxidase inhibitor activities. Cadmium toxicity is reported to causes oxidative damage, resulting in vascular dysfunction, reduced bioavailability of nitric oxide (NO) and hypertension. The study aimed to investigate the protective effects of apocynin in cadmium-induced hypertension. Thirty-six (36) adult male Sprague-Dawley rats were randomly divided into 6 groups. Group 1 served as control, Groups 2 and 3 received 50 and 100 mg/Kg (b.w) apocynin, respectively, Group 4 received 100 ppm CdCl2 in their drinking water, while Group 5 and 6 received 100 ppm CdCl2 in their drinking and 50 and 100 mg/Kg (b.w) apocynin, respectively, for 8 weeks. Blood pressure readings were taken weekly using the tail-cuff method. cGMP, endothelial nitric oxide synthase (eNOS), NO and hematological parameters were analyzed at the end of 8 weeks. Apocynin, although a poor antioxidant, caused a significant reduction (p < 0.05) in systolic and mean arterial pressures in the cadmium-induced elevations in blood pressure and amelioration of altered hematological parameters. However, while cadmium exposures did not alter the cGMP, eNOS and nitrate concentrations in serum, apocynin reduced the cGMP and nitrite values while significantly elevating (p < 0.05) the eNOS concentrations and also improved the cadmium-induced anemia. Apocynin was effective in reducing cadmium-induced elevated blood pressures through elevation of eNOS. Inhibition of NADPH oxidase activity may be a useful strategy for prevention and treatment of cadmium-induced hypertension.