RESUMO
The ultradian rhythm of the lateral leaflets of Desmodium motorium (Houtt.) Merril. was recorded with a picture analysis method using a video camera and a computer. The periods are in the minute range and depend strongly on temperature. The phosphatidyl inositol signal chain might be involved in the ultradian rhythm of the lateral leaflet movement of Desmodium motorium: Myoinositol shortens the period length and reduces the known period lengthening effect of lithium ions. Neomycin, which inhibits the hydrolysis of phosphatidylinositol-4, 5-biphosphate to inositol-4-phosphate and diacylglycerin, lengthens the period of the rhythm at low concentrations (0·2 mM). Higher concentrations shorten the period, perhaps by activating G protein. Mastoparan, which activates G protein, shortens period likewise. The G protein agonists fluorid ion and ethanol are toxic for the lateral leaflets and could therefore not be used to test the involvement of G protein. The intracellular Ca2+ antagonist 3, 4, 5-trinietlioxybeiizoic acid 8-(diethylamino)octylester lengthens the period of the rhythm. This indicates, that release of Ca2 + from intracellular stores is important for the lateral leaflet movement rhythm.