INFINITE CIS INFLUX OF CYCLIC-AMP INTO HUMAN-ERYTHROCYTE GHOSTS

Infinite cis uptake of cyclic AMP into red blood cell ghosts has been measured. The Kicoi is calculated from two different integrated rate equations that are applicable when the substrate concentration is unsufficient to cause volume changes. Values of 0.69 mM and 0.66 mM are obtained for the infinite cis Km at 30°C using these procedures. These values are only slightly higher than that predicted from zero trans net flux experiments. Lowering the temperature reduces Kicoi from 0.69 mM at 30°C to 0.478 mM at 20°C, 0.108 mM at 10°C and 0.072 mM at 4°C (Q10 = 2.4). The Q10 for activation of influx permeability of 10-5 M cyclic AMP is 1.55. © 1979.