Abstract
This article suggests that calcium acts as an intermediate for intestinal fluid secretion mediated by adenosine-3′:5′-cyclic monophosphoric acid (cAMP) and guanosine -3′:5′-cyclic monophosphoric acid (cGMP). It is hypothesized that microbial enterotoxins disrupt the normal interrelationships between calcium and cyclic nucleotides, thereby leading to adverse biological effects. It is further proposed that the inhibitory effect of chlorpromazine on calmodulin accounts for the ability of this drug to inhibit enterotoxins which separately elevate cAMP or cGMP concentrations.