This project is designed to assess the physiological importance of Ca2+-ions in the regulation of energy metabolism. Specifically, we have exposed isolated cardiac myocytes to a variety of conditions expected to alter cytosolic free Ca2+ concentration ([Ca2+]c), and have measured the amount of the active form of pyruvate dehydrogenase (PDH-A) which results, as well as estimating [Ca2+] by use of fluorescent chelating agents. Protocols used to increase [Ca2+]c include depolarization of the plasma membrane with KCl, abolition of the Na+c electrochemical gradient with ouabain and gramicidin, inhibition of sarcoplasmic reticulum Ca2+ uptake by caffeine and the use of metabolic inhibitors to deplete cellular ATP. We have demonstrated an increased value of PDH-A in response to each of these interventions, and an important role of Ca2+ transport into the mitochondria in mediating these increases. Further, we have taken advantage of the fluorescent chelating agent technology to characterize the mechanism of the increase in [Ca2+]c due to KCl-induced depolarization, and have established a sensitivity to beta -adrenergic agonists and to phorbol esters. We have also initiated a study of isolated hepatocytes, in order to investigate the importance of increased values of [Ca2+]c in mediating the increased activity of 2-oxoglutarate dehydrogenase and pyruvate dehydrogenase which occurs in response to the hormones glucagon and vasopressin.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Intramural Research (Z01)
Project #
1Z01AG000231-01
Application #
4687928
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
1
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Aging
Department
Type
DUNS #
City
State
Country
United States
Zip Code