Fig. 3.

Dependence of K⁺ current activation on G-proteins in HL-1 cells. a The bar charts summarise the results obtained. Treatment with pertussis toxin (100 ng/ml for 16 h) or tertiapin-Q (100 nM) led to inhibition of the carbachol-activated current (p < 0.01 for both). b Carbachol (10 µM) was applied four times for 1 min, with 1-min interval between applications, in the presence or absence of 0.3 mM GTP. Decline of the current elicited by carbachol was obtained only in the set of experiments where GTP was omitted (p < 0.05). c Currents were recorded for 3 min after break-in before addition of 10 µM carbachol in the presence of 30 µM intracellular GTPγS. Currents activated with dialysis of GTPγS into the cell (p < 0.05 compared with current at t = 0) and carbachol evoked smaller currents