抄録
Glucagon and fluoride ion stimulated the activity of adenyl cyclase in plasma membranes prepared from the livers of rats. The maximal stimulation produced by glucagon (1μg/ml) is 5 to 15times the basal activity, and the minimum effective concentration of glucagon was 1ng/ml.
Prostaglandin Et and insulin had no effect on the basal activity, and epinephrine showed only small stimulation of adenyl cyclase activity even at a high concentration. Insulin at varying concentrations did not inhibit the glucagon stimulated adenyl cyclase activity.
Sodium fluoride (10mM) also stimulated adenyl cyclase in plasma membranes, but the addition of fluoride ion failed to show further stimulation of adenyl cyclase activity when it was maximally stimulated by glucagon
Calcium ion, above 1×10-4M, inhibited the glucagon stimulated adenyl cyclase activity but the fluoride stimulation was not affected even at 5×10-3 M concentration. Trypsin digestion (10μg/ml, 5min at 37°C) or Lubrol PX treatment (0.02M, 5min) of plasma membranes resulted complete loss of the response to glucagon while the fluoride stimulation was remained.
These findings suggest that glucagon and fluoride ion are acting to stimulate a common adenyl cyclase through by different mechanisms.
