Comparative study of supersensitivity to K+ after denervation and decentralization in rabbit ear artery

The contractile response to potassium following denervation or decentralization of the central artery of the rabbit ear was studied in vitro. Denervation or decentralization for 8 weeks caused comparable supersensitivity to potassium: mean EC50 values obtained with isotonic high potassium solution were 21.3 mM in the denervated artery and 18.7 mM in the decentralized artery, and these values were significantly less than those (25-26 mM) of their respective contralateral control arteries (P less than 0.005, paired t-test). The maximum responses to potassium did not differ among the control, denervated and decentralized arteries. Phentolamine (3 X 10(-7) M) and propranolol (3 X 10(-7) M) had no significant effect on the response to potassium. Sensitivities to potassium with hypertonic high KCl solution and hypertonic high K2SO4 solution were virtually identical to those obtained with isotonic high potassium solution. The results suggest that denervation and decentralization produce identical postjunctional supersensitivity to potassium and that the lack of tonic activity of sympathetic nerves may be responsible for the phenomenon in the rabbit ear artery.