Specific supersensitivity of smooth muscle to angiotensin II after nephrectomy

1 The dose-response curves for angiotensin, 5-hydroxytryptamine and carbachol were obtained on rat uterus and colon excised 24 h after a bilateral nephrectomy or a sham operation.2 There was a shift to the left in the dose-response curves to angiotensin of organs from nephrectomized animals. Dose-response curves to 5-hydroxytryptamine and carbachol were not affected by nephrectomy.3 The interaction of the two competitive antagonists (1-Asn, 5-Ileu, 8-Ala)-angiotensin II and (1-Asn, 5-Ileu, 8-Ileu)-angiotensin II with angiotensin II receptors was tested in control and nephrectomized organs. There was a decrease of the K(I) values in colon muscle after nephrectomy.4 In conclusion, nephrectomy produces a specific supersensitivity to angiotensin that seems to be due to a change in the structure of angiotensin receptors, at least in colon smooth muscle. This increase in sensitivity may be the result of the elimination of a tropic factor that acts on angiotensin receptor sites.