LIPASE INHIBITORS ABOLISH CONTRACTIONS AND CAUSE DEPOLARIZATION IN FROG SKELETAL-MUSCLE FIBERS

Single, intact frog muscle fibres were exposed to bromophenylacylbromide (BPB) or nordihydroguairetic acid (NDGA). Fibres first became unable to respond to electrical stimulation and then depolarized; this process was accelerated by repeated activation. In addition BPB, but not NDGA, eventually induced a contracture in the fibre. The contractile response to direct Ca-release from the sarcoplasmic reticulum by caffeine was unaffected by the drugs.