Effects of protease, phospholipase and neuraminidase on the Ca2+- receptor of the frog tongue

Effects of some proteases, phospholipases and a neuraminidaseon the Ca²⁺-receptor of the frog tongue were studied by recordingneural responses from single fungiform papilla preparationsbefore and after application of the enzymes. The results obtainedwere as follows: 1) Trypsin, -chymotrypsin, pronase and highconcentrations of phospholipase-C inhibited the Ca²⁺-responseof the receptor irreversibly. 2) Ficin, phospholipase-D andlow concentrations of phospholipase-C inhibited the Ca²⁺-responsetemporarily, and the response recovered 10 to 20 min after removalof theenzymes. A similar temporal inhibition was produced byneuraminidase, but the recovery was more gradual than in thecases of ficin and phospholipases. 3) Phospholipase-A hardlyproduced any significant effects on the Ca²⁺-response. Basedon these results, the characteristics of the Ca²⁺- receptorof the frog tongue were considered.