A K(+)/H (+) P-ATPase transport in the accessory cell membrane of the blowfly taste chemosensilla sustains the transepithelial potential.
An electrogenic K(+) transport in the tormogen cell of insect chemosensilla is involved in the generation and maintenance of the transepithelial potential (TEP). To gain more information about the K(+) transport system underlying the TEP generation and the location of its components in the plasma membrane of the tormogen cell, we studied the effects of inhibitors of K(+)/H(+) P-ATPase (bafilomycin A1, omeprazole and Na-orthovanadate), of K(+)/Cl(-) co-transport (bumetanide), of Cl(-) channels (NPPB) and of a K(+) channel blocker (BaCl(2)). The relationship between TEP amplitude and spike firing activity was also studied. Experiments were performed on the labellar chemosensilla of the blowfly Protophormia terraenovae using a modified tip-recording technique. Results show that: (a) K(+)/H(+) P-ATPase inhibitors significantly decrease the TEP, when properly applied to the labellum for 20 min, so as to reach the basolateral side of the plasma membrane, while no effect was detected when applied to the apical side, (b) bumetanide, NPPB and BaCl(2) decrease the TEP value only when administered to the apical side, (c) spike activity is positively correlated with the TEP. A model is proposed of the active and passive K(+) transports sustaining the TEP associated with the blowfly chemosensilla.
Sollai
Giorgia
G
Department of Experimental Biology, University of Cagliari, Cittadella Universitaria, 09042, Monserrato (CA), Italy.
Solari
Paolo
P
Masala
Carla
C
Liscia
Anna
A
Crnjar
Roberto
R
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000251:Adenosine Triphosphatases / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004175:Diptera; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects / Q000502:physiology*; D017506:H(+)-K(+)-Exchanging ATPase / Q000378:metabolism*; D008954:Models, Biological; D015221:Potassium Channels / Q000502:physiology; D011189:Potassium Chloride / Q000494:pharmacology; D012679:Sense Organs / Q000166:cytology* / Q000187:drug effects / Q000502:physiology
D004791:Enzyme Inhibitors; D015221:Potassium Channels; D011189:Potassium Chloride; D000251:Adenosine Triphosphatases; D017506:H(+)-K(+)-Exchanging ATPase