Animal and human organs appear to have diminished physiologic responsiveness to catecholamines in the setting of respiratory or metabolic acidosis. The proposed work will examine the biochemical mechanisms through which metabolic acidosis may interfere with the action of beta-adrenergic receptors on human neutrophils. These studies will identify specific changes in the components of the beta-adrenergic receptor-adenylate cyclase system. Thus, there may be changes in the receptor density, in """"""""coupling"""""""" of receptor occupation with enzyme activation, or in the activity of the enzyme adenylate cyclase. Studies will be performed to determine whether these regulatory changes are mediated by an alteration in pH, by the presence of organic acids, or by an alteration in the oxidation-reduction potential in the environment to which these cells are exposed. Once the pattern and mechanism of regulation by metabolic acidosis is identified, the relationship of these effects to regulation induced by steroids and catecholamines will be investigated. The separate and combined effects of steroid and catecholamine will be studied in order to produce a model of receptor regulation representing the complex clinical state of metabolic acidosis in which alterations in steroid and catecholamine concentrations exist. These studies will both further illuminate the mechanism of receptor regulation and will also provide a foundation for therapeutic endeavors. The results of the in vitro model will be validated by examining cells derived from patients experiencing metabolic acidosis. The evidences of regulation of beta-adrenergic receptors on these cells derived from patients will be compared and contrasted to the predicted regulatory effects based upon the in vitro work. Finally, studies will be made of beta-adrenergic receptor regulation occurring in clinical states such as lactic acidosis, diabetic ketoacidosis, alcoholic ketosis, and poisoning. Thus, these studies are expected to provide insight into the biochemical process of receptor regulation, to form a foundation for therapeutic endeavors, and to enhance understanding of alterations in human physiology based upon biochemical responses to illness.
| Balasubramanyam, A; Davies, A O; Codina, J et al. (1991) Abnormal Gs function in mitral valve prolapse dysautonomia is not associated with abnormal alpha S cDNA sequence. Life Sci 48:789-93 |
| Davies, A O; Su, C J; Balasubramanyam, A et al. (1991) Abnormal guanine nucleotide regulatory protein in MVP dysautonomia: evidence from reconstitution of Gs. J Clin Endocrinol Metab 72:867-75 |
| Mares Jr, A; Davies, A O; Taylor, A A (1990) Diversity in supercoupling of beta 2-adrenergic receptors in orthostatic hypotension. Clin Pharmacol Ther 47:371-81 |
| Montamat, S C; Davies, A O (1989) Physiological response to isoproterenol and coupling of beta-adrenergic receptors in young and elderly human subjects. J Gerontol 44:M100-5 |
| Davies, A O (1988) Exercise-induced fall in coupling of human beta 2-adrenergic receptors. Metabolism 37:916-8 |
