Fig. 3. In vitro desensitization of the -adrenoceptor in cells of the Bothrops jararaca venom gland. Quiescent cells were incubated for 5 min with 10^–4 mol l^–1 noradrenaline and kept at 30°C for 24 h(triangles, N=6) before the construction of the dose–response curve to phenylephrine. Control quiescent cells (squares, N=11). Note that incubation with noradrenaline induced receptor downregulation. Values are means ± S.E.M.