Fig. 9. Continuous perfusion with caffeine saline (10 mmol l^-1) reduced or eliminated tetani, but had little effect on basal tonus. In both traces the peptide-induced contracture developed more rapidly and was greater in amplitude during the period of caffeine exposure then before. The recovery of the contracture was faster than in the absence of caffeine. Note the rapid recovery of tetani immediately following the washout of caffeine in (B).