AIM To investigate the special changes in resistance vessel reactivity to vasomotor stimuli and analyze the effect and concerned
mechanism of tetrandrine on those changes in
renovascular hypertensive(RH) rats. METHODS The contraction and relaxation of resistance vessels to stimuli were investigated in
tail artery and mesenteric arteriole bed. RESULTS Compared with sham-operated rats, the isolated mesenteric arteriole bed and tail artery exhibited an enhanced reactivity to norepinephrine(NE) induced vasoconstriction, with an increase in maximum vasoconstriction and a decrease in vasodilation produced by acetylcholine and sodium nitroprusside. The sensitivity of tail artery to methylene blue, an inhibitor of guanylate cyclase, was greatly reduced. The amplitude of elevated pressure in mesenteric artery bed after removal of endothelium was attenuated. The changes mentioned above were greatly improved in tetrandrine treated RH rats. CONCLUSION In RH rats, the reactivity of resistance vessels to vasoconstrictive stimuli is increased, whereas the reactivity to both endothelium dependent or independent vaso-relaxative stimuli are reduced. Tetrandrine 50 mg·kg -1·d -1 for 9 weeks significantly reverse those changes by preserving endothelium functions and guanylate cyclase activity.