Age-dependent abnormalities in the function of urinary tract smooth muscle may lead to deterioration in renal structure and function and/or may result in incontinence with its resultant medical, psychological, sociological, and economic implications. These functional changes may result from alterations in regulatory mechanisms or from changes in membrane structure or composition. The unifying hypothesis of this proposal is that aging causes changes in the biochemical and functional properties of urinary tract smooth muscle, and that these changes may in turn influence the response of these tissues to pharmacologic manipulation and pathologic insult. The long-term objective is to determine both how and why age affects the function of urinary tract smooth muscle. To achieve this goal, we will study changes in ureteral-vesical function with age at the level of 1) signal recognition (hormone-receptor complex); 2) signal transmission (transduction of the signal generated by the interaction of an agonist or hormone with a receptor from the outside of the plasma membrane to the inside of the cell where a biochemical and ultimately a physiologic event occurs); and 3) signal functional response (response to the transmitted signal as measured by changes in contractile force). We plan to: 1) define the physiological parameters involved in receptor regulation, i.e., the regulatory effects of gonadal hormones on the receptor-effector system, 2) characterize and localize autonomic and calcium antagonist receptor subtypes 3) determine the regulatory effect of G-proteins in the transduction of the hormone-receptor signal in adrenergic, muscarinic cholinergic, and calcium antagonist receptor systems, 4) determine how changes in membrane structure and composition that occur with aging affect the functional response of urinary tract smooth muscle, 5) determine the role of the second messengers, i.e., cyclic AMP, cyclic GMP, Ca++ and the products of inositol phospholipid metabolism (inositol trisphosphate, IP3, and diacylglycerol, DG) in the age-dependent functional changes of urinary tract smooth muscle, and 6) determine how age-dependent changes in signal recognition and signal transmission affect the functional response to Ca++ and its agonists and antagonists, membrane perturbers, and potassium channel agonists and antagonists. The determination of how age affects the function of urinary tract smooth muscle and the response of the smooth muscle to pharmacologic agents may provide a rationale for the development of new drugs for the treatment of pathologic states.
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