“ LPMD also inhibited the Isc increments … increase 3‘,5’-cyclic adenosine monophosphate (cAMP) content (theophylline and prostaglandin E2) or by the Ca2+ ionophore A23187; the opiate, however, did not prevent the …‘,5’-cyclic guanosine monophosphate (cGMP)-related agents such as 8-Br-cGMP and Escherichia coli heat-stable enterotoxin.”