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 Koiic 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 degrees C using these procedures. These values are only slightly higher than that predicted from zero trans net flux experiments. Lowering the temperature reduces Koiic from 0.69 mM at 30 degrees C to 0.478 mM at 20 degrees C, 0.108 mM at 10 degrees C and 0.072 mM at 4 degrees C (Q10 = 2.4). The Q10 for activation of influx permeability of 10(-5) M cyclic AMP is 1.55.