P-31 NMR INVESTIGATION OF ENERGY-METABOLISM IN PERIFUSED MMQ CELLS

The MMQ cell line is a unique prolactin-secreting rat pituitary cell l ine. MMQ cells entrapped in agarose gel threads are metabolically acti ve, as determined by the uptake and phosphorylation of creatine and th e maintenance of high energy phosphates for over 15 h. Forskolin activ ates the catalytic subunit of adenylyl cyclase and, in MMQ cells, elev ates the level of cAMP and stimulates prolactin secretion. P-31 NMR sp ectroscopy was used to investigate the energy metabolism of the MMQ ce lls during stimulation by forskolin. The ability to measure small chan ges in the energy status of these cells was enhanced by increasing the PCr levels in the cells. Administration of forskolin to the perifused MMQ cells resulted in acute, reversible, and dose-dependent changes i n the P-31 NMR spectra of the cells within 12 to 24 min of the beginni ng of forskolin exposure. Several lines of evidence indicate that the changes observed in the MMQ cells are the composite result of the inte raction of forskolin with adenylyl cyclase and the plasma membrane glu cose transporter. Also, preincubation of the MMQ cells with the dopami ne agonist, bromocriptine, attenuates the forskolin-stimulated decreas e in the PCr resonance by approximately 50%. This attenuation indicate s that the forskolin-stimulated changes in energy metabolism are proba bly related to the prolactin secretion process.