Fig. 9. Model for HCO3 formation and its linkage to Na+ transport in the ciliary processes. Observed rates are for monkey. Chemical rate constants (37°C) taken from the work of Maren. (From Maren TH: The kinetics of HCO3 synthesis related to fluid secretion, pH control, and CO2 elimination. Annu Rev Physiol 50:695, 1988, with permission.)