Fig. 5. Dose–response of the effects of cGMP on the basolateral membrane voltage V_bl (A), and the input resistance R_pc (B) of principal cells in isolated Malpighian tubules of A. aegypti. The insert in A illustrates the usual biphasic response of V_bl to 500 µmol l^–1 cGMP. Values are means ± S.E.M.; the number of principal cells is indicated for each data point; ^*P<0.05, paired Student's t-test. Open circles, steady state depolarization; closed circles, peak depolarisation.