CELL-FREE filtrates of cultures of V. cholerae contain a toxin which produces fluid accumulation in ligated rabbit ileal loops1 and increases capillary permeability in rabbit skin2. In isolated rabbit ileal mucosa, it induces chloride secretion and inhibition of normal, non-glucose mediated sodium absorption3. The effects on ion fluxes are similar to those produced by theophylline or cyclic adenosine 3'5'-monophosphate (cAMP) and, in addition, the effects of cholera toxin on gut fluid loss are mimicked by agents that can increase tissue cyclic AMP levels4. We therefore investigated the effects of the toxin on fat cells in which accumulation of cAMP resulting either from increased synthesis (for example, with epinephrine) or from decreased degradation (for example, with theophylline) results in stimulation of lipolysis5. As reported below, cholera toxin increases glycerol production by fat cells. These studies have provided the basis for a simple, sensitive assay for choleragen.
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