We have been studying the basic biochemical mechanisms whereby the type of dietary lipids can affect the salivary gland cell function. The working hypothesis being investigated is that dietary lipids can induce changes in structural lipids and fluidity of the cell membranes, which results in modification of membrane function. In vivo changes can be induced in membrane lipids by essential fatty acid deficiency, cholesterol-rich diets and diets containing high levels of omega-3 fatty acids. Changes in membrane lipids result in altering beta-receptor adenylate cyclase system, which consists of the receptor, G-proteins and adenylate cyclase. Further studies will be conducted using these nutritional models to determine their effects on each of the 3 components of the adenylate cyclase system in the rat submandibular salivary gland (SMSG). Studies will also be conducted with dispersed SMSG cells from rats fed various diets in order to determine if the diet-induced changes in membrane lipids and adenylate cyclase system would result in. functional changes such as the secretion of glycoproteins. Diet-induced changes in membrane fluidity will be assessed by measuring fluorescence polarization and lifetimes of the excited states for diphenylhexatriene and 16-anthroyloxy palmitate after their incorporation into the SMSG membranes. Because of the microsomal fatty acid desaturases are considered to be important in the regulation of membrane fluidity and in the metabolism of essential fatty acids, their specific activities in the SMSG, along with their dietary modulation, will be studied.
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