The effect of local anaesthetics on noncholinergic-nonadrenergic (NCNA) responses of the gut.

The newly synthesized carbamate local anaesthetics (heptacaine and BK-141) affected the NCNA responses of different segments of the guinea-pig small (jejunum, ileum) and large (colon, taenia coli) intestine in a similar manner to the classic local anaesthetics (procaine and trimecaine). The sensitivity of NCNA responses to the action of local anaesthetics was, in order: primary contraction greater than rebound contraction greater than primary relaxation. The action of the carbamate local anaesthetics resembled that of trimecaine more than that of procaine. The results presented suggest that different Ca2+ channels participate in primary and rebound contraction and that local anaesthetics affect the receptor-operated Ca2+ channels in lower concentrations than the voltage-dependent ones.