Chronic Tea Consumption Lowers Blood Pressure in Rats: Some Associated Mechanisms
AbstractThe study was designed to investigate the effect of chronic tea consumption (1.76g/kg b wt/day/rat for 42 days) on blood pressure (BP), heart rate (HR) and cardiovascular responses to bilateral carotid occlusion (BCO), coupled with some associated mechanisms. Five experiments were performed in paired weight matched groups of rats (n = 5). In the first experiment, group 2 (kept on normal feed; NF and tea drink) had lower systolic, diastolic and mean arterial pressure (MAP) (P < 0.005) compared with group 1 (kept on NF and normal drinking water), with little change in HR and cardiovascular reflex. Experiments 2 to 5 were used to investigate some mechanisms responsible for the hypotensive effect of tea using appropriate pharmacologic blockers. In experiment 2, group 3 (kept on NF and furosemide solution) had similar BP as group 4 (kept on furosemide, NF and tea). In experiment 3, group 5 (kept on NF and captopril solution) had similar BP as group 6 (kept on captopril, NF and tea). In experiment 4, group 7 (kept on NF and nifedipine solution) had similar BP as group 8 (kept on nifedipine, NF and tea). In experiment 5, group 9 (kept on NF and indomethacin solution) also had similar BP as group 10 (kept on indomethacin, NF and tea). The results suggest that chronic tea consumption lowers BP in rats with little change in HR and cardiovascular reflex. The hypotensive effect of tea may be attributed to the following mechanisms: the prostanoids, sodium/potassium transport, calcium transport and the RAS (producing the least contribution).
KEY WORDS: Blood pressure (BP), heart rate (HR), rats, tea.
Nigerian Journal of Health and Biomedical Sciences Vol.3(2) 2004: 131-135