Growth stimulation by bombesin does not involve activation of Na+/H+ exchange in chick embryo otic vesicles in vitro.
The effect of the mitogen bombesin on pHi in cells of the chick otic vesicle was studied using dual wavelength micro-spectrofluorimetric techniques. The results show that the bombesin did not produce an immediate alkalinization in quiescent otic vesicle cells nor a long-term change in pHi in vesicles reactivated to grow in culture. The recovery of pHi from an acid load, caused by an NH4 pulse, involved both Na+/H+ exchange and Na+:HCO3 influx mechanisms, neither of which was influenced by bombesin. These observations do not fit with a general model whereby pHi is a universal signal for DNA replication and cell proliferation.
Gillespie
J I
JI
Department of Physiological Sciences, Medical School, The University, Newcastle upon Tyne, England.
Giraldez
F
F
Greenwell
J R
JR
D000818:Animals; D001839:Bombesin / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D002642:Chick Embryo; D004261:DNA Replication / Q000187:drug effects; D007758:Ear, Inner / Q000166:cytology* / Q000187:drug effects / Q000196:embryology; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D009924:Organ Culture Techniques; D017923:Sodium-Hydrogen Exchangers
D002352:Carrier Proteins; D007328:Insulin; D017923:Sodium-Hydrogen Exchangers; D001839:Bombesin