Temperature-dependent specific desensitization in the rat anococcygeus muscle to angiotensin II

The effect of angiotensin II (A II) on isolated rat anococcygeus muscle was investigated. A II, when used submaximally (4 X 10(-9) mol/l), produced a rapid contraction of the rat anococcygeus muscle. However, a profound tachyphylaxis developed with repeated administrations. This tachyphylaxis is specific in nature, since the tissue responded normally to noradrenaline even after the establishment of a complete tachyphylaxis to the peptide. Incubation with phentolamine or indometacin had no effect on the A II-induced tachyphylaxis. On the other hand, a marked prevention of tachyphylaxis was obtained by lowering the bath temperature to 31 or 25 degrees C. These results indicate that neither noradrenaline nor prostaglandin release participate in the development of tachyphylaxis to A II in rat anococcygeus muscle, and this tachyphylaxis can be prevented by lowering the temperature of the bath solution.