Figure 7. I_Cl,swell generation and its relation with a likely ACh or ATP release elicited by cell swelling.

A, current traces correspond to the control I_Cl,swell activated by HR₈₀ superfusion alone (upper trace) and in the presence of 10 μM pirenzepine (lower trace), a potent antagonist of muscarinic receptors in follicles. Similar results were obtained in 7 follicles more from 3 frogs. B, in follicles from the same frogs used in A, the muscarinic responses were completely inhibited by superfusion with the antagonist. The example traces showed that the typical oscillatory Ca²⁺-dependent chloride current elicited by 10 μM ACh was effectively eliminated by pirenzepine. C, F_in currents were elicited by short pulses of 1 μM ATP ejected periodically from a pipette positioned close to the follicle; each ejection pulse was applied after the voltage step of 20 mV (arrow). For the time indicated, 5 μM ATP in NR was superfused; while this solution is present in the bath and after its corresponding F_in was elicited, the F_in generated by the 1 μM ATP jets was potently inhibited. Similar results were obtained in 8 follicles from 3 different frogs. D, similar F_in currents generated by 1 μM ATP pulses were not decreased when I_Cl,swell was simultaneously generated; nevertheless, a transient potentiation of 30–60 % (*) was noted during the first minutes during I_Cl,swell activation in 4 experiments from 10 follicles tested (3 frogs).