Permeable analogues of cGMP promote hepatic calcium inflow induced by the synergistic action of glucagon and vasopressin but inhibit that induced by vasopressin alone Available to Purchase

Treatment of perfused rat liver with the nitric oxide-generating reagent molsidomine led to substantial increases in cGMP without itself affecting basal Ca²⁺ fluxes. Under these conditions the ability of glucagon plus vasopressin to induce Ca²⁺ influx was greatly enhanced. The permeable analogue of cGMP (8-bromo-cGMP) enhanced glucagon plus vasopressin-induced Ca²⁺ influx to a similar extent as that with molsidomine. This suggests that the effect of the latter is attributable to the generation of cGMP which itself enhances the ability of the two hormones to induce synergistic Ca²⁺ influx. While 8-bromo-cGMP (or molsidomine) did not influence Ca²⁺ fluxes induced by glucagon, these agents strongly inhibited Ca²⁺ influx induced by vasopressin alone. These data show that while 8-bromo-cGMP has no effect on basal Ca²⁺ fluxes, it is able to modify the Ca²⁺ influx induced by glucagon and vasopressin action in hepatic tissue.