Masamitsu Hamaguchi

Energy metabolism in unrestrained fish with in vivo 31P-NMR

Abstract 1. 1. We evaluated changes in high energy phosphate metabolism in unrestrained freshwater loaches by in vivo 31 P-NMR. 2. 2. When dissolved oxygen was deficient, both an increase in Pi and a decrease in PCr were observed as the loach struggled. 3. 3. After pretreating the fish with an anesthetic agent, we observed the dependence of high energy phosphate metabolism on changes in dissolved oxygen. 4. 4. Under anesthetic [Pi]/[Pi] + [PCr] ratio, an index of metabolic state, was lower than without anesthesia. 5. 5. Decrease in high energy phosphate metabolism in fish during oxygen deficiency was not caused by poor oxygen supply but resulted from struggle movement due to lack of oxygen.

Changes in high-energy phosphate metabolites in loaches (cobitis biwae) during 2-phenoxyethanol anesthesia

Abstract 1. We evaluated changes in high-energy phosphate metabolism in the muscle of loaches during 2-phenoxyethanol (2-PE) anesthesia by 31 P-NMR. 2. The creatine phosphate (PCr) concentration increased while the inorganic phosphate (Pi) concentration decreased in the muscle as 2-PE anesthesia was continued, but both returned to the preanesthetic values with recovery from the anesthesia. 3. The sugar phosphate (SP) concentration also increased during anesthesia, but SP did not disappear after recovery. 4. In the muscle of loaches anesthetized with 2-PE, the phosphate metabolism was aerobic, but carbohydrate metabolism was suppressed.

Changes in activity of substantia nigra pars reticulata neurons after middle cerebral artery occlusion in the rat

The spontaneous single unit activity of substantia nigra pars reticulata (SNR) neurons was studied in control and in ipsilateral middle cerebral artery (MCA) -occluded rats. The activity of MCA-occluded preparations was recorded in 3 groups; 1 hour, 24 hours, and 7 days after MCA occlusion. Activity was recorded extracellularly with glass microelectrodes and was analyzed using time interval histograms. In the control, half of the SNR units (47%) showed a regular firing pattern. There was no change 1 hour after MCA occlusion. After 24 hours and 7 days, however, there was increased SNR neuronal unit activity with irregular firing patterns (67% and 57%, respectively), and a slightly decreased mean firing rate. In the MCA-occluded groups, no hyperexcited neurons at all were found in the SNR. Our results indicated that SNR neuronal degeneration accompanied by striatal ischemia does not depend simply on hyperexcitation due to a disinhibition mechanism.

Energy metabolism during contraction of the first ambulatory leg of the crayfish

Abstract 1. 1. The metabolism of high energy phosphates during contraction of muscle in the first ambulatory leg of the crayfish, Procambarus clarkii, by neural stimulation was evaluated by 31P-NMR. 2. 2. When the chela nerve was stimulated, the phosphoarginine (Arg-P) concentration showed no clear change with the first five stimuli, but shortly thereafter a decrease was observed with an elevation in Pi muscle stimulation. 3. 3. The rate of Arg-P decrease was not dependent on stimulus frequency. 4. 4. The pH changes were more marked in the case of direct electrical stimulation, and reached about 80% of the initial concentration under aerobic conditions and about 95% under anaerobic conditions.