The “Direct” Effect of Physalaemin on Salivary Gland Cells

It is generally assumed that salivary gland cells can be excited only by the transmitters of their secretory nerves or by drugs which mimic the action of the transmitters. Since the time of Claude Bernard ( Recently, however, a " direct " sialogogue effect has been attributed to physalaemin. This endecapeptide, originally extracted from the skin of the South American amphibian Physalaemus fuscumaculatus by Erspamer, Bertaccini & Cei (1962) and later synthesized by Bernardi, Bosisio, Goffredo & De Castiglione (1964), was found to have a powerful secretory effect on some salivary glands This effect was analysed by Bertaccini & De Caro (1965), who found that it was particularly pronounced in dogs and rats and that it could be abolished neither by atropine nor by sympatholytic agents. The action was therefore described as " direct," although it was pointed out that an action via adrenergic f-receptors could not be entirely ruled out; the only fl-receptor blocking drug