Bombesin activates large-conductance chloride channels in Swiss 3T3 fibroblasts.
Using the patch-clamp technique (cell-attached patches), we found that bombesin, a Ca-mobilizing peptide mitogen, activates large-conductance Cl channels in Swiss 3T3 fibroblasts. The channel activation required a lag period of about 50 s and was equally observed whether bombesin was applied to the patch-pipette or to the bath. A23187 (10(-6)M) in the bath induced the similar currents with almost identical current-voltage relationship as bombesin: their slope conductances were 292 +/- 15 (bombesin) and 318 +/- 42 (A23187) pS. In inside-out patches, the induced channels were selective to Cl over gluconate (11:1). These observations strongly suggest that in Swiss 3T3 fibroblasts bombesin activates the Cl channels through a mechanism involving an increase in the intracellular free Ca concentration.
Kawahara
K
K
Department of Physiology, Faculty of Medicine, University of Tokyo, Japan.
Takuwa
N
N
D000818:Animals; D001839:Bombesin / Q000494:pharmacology*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D018118:Chloride Channels; D004553:Electric Conductivity; D005347:Fibroblasts / Q000502:physiology; D007473:Ion Channels / Q000502:physiology; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D013816:Thermodynamics
D018118:Chloride Channels; D007473:Ion Channels; D008565:Membrane Proteins; D000001:Calcimycin; D001839:Bombesin; D002118:Calcium