. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. -Vm=-60 mV Vm=-80 mV 10 15 20 25 30 TIME (s) 35 Figure 8. Response to ACh in whole-cell recording configuration. Pipet solution contained (in mA/) 20 NaCl. 406 , 2 MgCU, 100 HEPES. 5 EGTA, 5 MgATP, NaGTP. 10 glutathione, pH (ad- justed with KOH). Fibers were constantly superfused with artificial sea- water. Holding potential was -80 mV and was moved to -65 mV every 3s. A 15-s pulse of 10~5 M ACh elicited inward current at both membrane potentials. suction-activated channel, determined by eliciting channel activit
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. -Vm=-60 mV Vm=-80 mV 10 15 20 25 30 TIME (s) 35 Figure 8. Response to ACh in whole-cell recording configuration. Pipet solution contained (in mA/) 20 NaCl. 406 , 2 MgCU, 100 HEPES. 5 EGTA, 5 MgATP, NaGTP. 10 glutathione, pH (ad- justed with KOH). Fibers were constantly superfused with artificial sea- water. Holding potential was -80 mV and was moved to -65 mV every 3s. A 15-s pulse of 10~5 M ACh elicited inward current at both membrane potentials. suction-activated channel, determined by eliciting channel activity at several different holding potentials, averaged 140 ± 20 pS (n = 3), as exemplified by the patch illustrated in Figure 7. After gigaseal formation, whole cell configuration could be achieved by applying greater suction than is necessary to activate suction-activated channels. With a pipet so- lution containing high potassium and other ingredients meant to mimic the normal intracellular milieu of the fibers (complete composition is given in the caption to Fig. 8), ACh elicited an inward current (Fig. 8). The peak current elicited by 10 5 M ACh at a holding potential of -80 mV was ± nA (n = 20); at a holding po- tential of -60 mV. the peak current averaged ± nA (n = 20). Under the same ionic conditions, depolar- ization activated outward current (Fig. 9). In observations of more than 20 cells, a net voltage dependent inward current was never seen under conditions of having high potassium in the pipet and normal sea water outside. Oc- casionally, there was a slight delay in activation of outward current (not seen in Fig. 9), possibly indicating an initial counterbalancing inward current. Voltage-dependent inward current can, however, be seen under conditions that block potassium channels. With cesium in the electrode and 4-aminopyridine and tetraethylammonium in the extracellular solution, de- polarization elicited an inward current. The peak inward curren
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
