Fig. 4. Comparison of secretory response to cyclic AMP and Tenmo-DH₃₇ (DH37). No significant differences in the response time or maximum rates of secretion were observed when Malpighian tubules of Tenebrio molitor were stimulated with 1 mmol l^–1 cyclic AMP (broken line) or 100 nmol l^–1 Tenmo-DH₃₇ (solid line). Each point shows the mean ± S.E.M. for 8–12 tubules. The horizontal filled bar indicates the period during which tubules were exposed to either cyclic AMP or Tenmo-DH₃₇.