- Email: [email protected]
Comparison of effects of DNP on the cells of various portions in the canine ventricle
~OCOMPARISON OF EFFECTS OF DNP ON THE CELLS OF VARIOUS PORTIONS IN THE CANLNE VENTRICLE. A. Kamiyama, R. Shibayama. Department of Physiology, School of MediN-ine Teikyo University, Tokyo, Japan. Effects of metabolic inhibition are known to make difference tn elrctrophysi~~logical responses of cells in the various portions of the herat. In the present exp-2 riment, changes in configuration of the action potential after the .lpplication of 10 M dinitrophenol (DNP) were studied by the microelectrode techinque in Purkinje fibers, subendocardial ventricular muscles, and rightand left-subepicardial muscles. Maximum rate of rise, amplitude and 50% duration were measured from the action potential as main parameters, and sumetimes the measurements of height of pl.lteau level and of mechanical response were added. All parameters diminished within 5 minutes in all kinds of muscles described above. Three main parameters of the Purkinje fiber and subendocardial ventricular muscles recovered to contrc>l values even in the medium containing DNP, but those of subepicardial muscles never recovered. p.w"", such recovering in the endocardial muscles was abolished by pretreat of 10 M owbain. Preaddition of 5OmM glucose trended tu prolonge the time coursr of diminishing in the values of main parameters. MOt-eoVei-, sllbrpicardial actiun potentials deteriorated by DNP trended to transiently recovri by addition of 50 mM glucose. From the results mentioned above, it was conclwed that the cells in the various portions of the canine ventricle respond to DNP in same mznner, except the sp<,nt,ineoiis rw-ilvery. POTASSIUM AND BUFFER ON THE RESPIRATORY OF CALCIUM, RAT HEART. E. schraven and C. Gruber. Department of Medical Cassella AG, 6000 Frankfurt (Main,, West Germany.
71 INFLUENCE
QUOTCEN'I OF THF: ISOLATED and Eiolooicsl Research,
The myocardial respiratory quotient (RQ; ratlo of CO?-production to 01-consumption) represents an indirect measurement of the preferentially metabolized substrate, FFA or qlucose. RQ, flow and lactate production were measured in LANGENDORFF-perfused, isolated rat hearts. TYRODE-solution and HEPES-buffer with normal (l.ti mM) and halfnorma1 (0.9 mM) calcium and normal (2.7 mM) and doubled ( 5.-l mM) potassium concentrations were used. The RQ was nearly 0.7 under all conditions studied. The flow increased from 6 to 7 ml/min to 9 - 10 ml/mln with decreaslnq Cd++-concentration. Lactate pmduction was higher in HEPES-buffers compared to TYRODE-solutions. Carbocromen (C) was reported to increase the RQ from 0.7 to 1.0 (K. Giittler et al. Naunyn-S. Arch. Pharmacol., 308 (1979) R 38). This effect could be confirmed for the TYRODE-solutions, but not for HEPES-buffers. The flow was significantly incwased by C only in solutions with "normal" Cd++-concentrations. A1sc.1 undvr C the lactate production was hiqher in HEPES-buffers than in TYRODE-solutions. These results seem to show that the metabolic effects whereas the hemodynamic actions are in TYRODE-solutions, with "normal" calcium.
of C are Freferentlally seen more pronounced 1n buffers
72CELLULAR UPTAKE OF 13N-Al+lONIA, A MARKER USED IN MYOCARDIAL SCINTIGHAPHY D.Hauch,~l.Crunze,F.Helus,E.Braunwell,H.Hasselbach,W.K~~bler.Abt.Innere Med.111 d.Universitit, Nuklearmed. Inst.. DKFZ u. Max-Planck Inst. f.med. Forschuny , Heidelberg. To study kinetics of cellular uptake of 13H-ammonia (1311),heart muscle cells of adult rats were isolated by perfusion with collaqenase. Net uptake of 13N was measured by flow dialysis.Extracellular 13N-con= centration was ~DOJJIJ at the begin of the reaction.13N was produced in the cyclotron by the 16 O(p,tii)-13N reaction.kesults:l)In the presence of bi= carbonate and carbon dioxide (medium I) 13N-activity was extracted by a rate constant k=7,6/min,reaching an intra-extracellular yradient of 13:l within 30 seconds.2)Cells.destroyed by calcium overload,did not extract 13N.3)Replacement of medium I by a buffer solution without hicarbonate and carbon dioxide (medium II) reduced total extraction (TE) by 60% and k by 83%.4)Preincubation of 4,4’diisothio2,2’stilbene disulfonic acid (DIDS),an inhibitor of anion exchanye systems,in medium I similarly re= duced TE by 66%,while k was not affected.5)Inhibition of glutamine syn= thetase by 1-methionine sulfoximine reduced TE by 50% and k by 69%. The results indicate that,in addition to metabolic trapping,13N uptake in myocytes depends on intracellular buffer capacity,probably mediated by an anion exchange system in the cell membrane.
71 INFLUENCE
QUOTCEN'I OF THF: ISOLATED and Eiolooicsl Research,
The myocardial respiratory quotient (RQ; ratlo of CO?-production to 01-consumption) represents an indirect measurement of the preferentially metabolized substrate, FFA or qlucose. RQ, flow and lactate production were measured in LANGENDORFF-perfused, isolated rat hearts. TYRODE-solution and HEPES-buffer with normal (l.ti mM) and halfnorma1 (0.9 mM) calcium and normal (2.7 mM) and doubled ( 5.-l mM) potassium concentrations were used. The RQ was nearly 0.7 under all conditions studied. The flow increased from 6 to 7 ml/min to 9 - 10 ml/mln with decreaslnq Cd++-concentration. Lactate pmduction was higher in HEPES-buffers compared to TYRODE-solutions. Carbocromen (C) was reported to increase the RQ from 0.7 to 1.0 (K. Giittler et al. Naunyn-S. Arch. Pharmacol., 308 (1979) R 38). This effect could be confirmed for the TYRODE-solutions, but not for HEPES-buffers. The flow was significantly incwased by C only in solutions with "normal" Cd++-concentrations. A1sc.1 undvr C the lactate production was hiqher in HEPES-buffers than in TYRODE-solutions. These results seem to show that the metabolic effects whereas the hemodynamic actions are in TYRODE-solutions, with "normal" calcium.
of C are Freferentlally seen more pronounced 1n buffers
72CELLULAR UPTAKE OF 13N-Al+lONIA, A MARKER USED IN MYOCARDIAL SCINTIGHAPHY D.Hauch,~l.Crunze,F.Helus,E.Braunwell,H.Hasselbach,W.K~~bler.Abt.Innere Med.111 d.Universitit, Nuklearmed. Inst.. DKFZ u. Max-Planck Inst. f.med. Forschuny , Heidelberg. To study kinetics of cellular uptake of 13H-ammonia (1311),heart muscle cells of adult rats were isolated by perfusion with collaqenase. Net uptake of 13N was measured by flow dialysis.Extracellular 13N-con= centration was ~DOJJIJ at the begin of the reaction.13N was produced in the cyclotron by the 16 O(p,tii)-13N reaction.kesults:l)In the presence of bi= carbonate and carbon dioxide (medium I) 13N-activity was extracted by a rate constant k=7,6/min,reaching an intra-extracellular yradient of 13:l within 30 seconds.2)Cells.destroyed by calcium overload,did not extract 13N.3)Replacement of medium I by a buffer solution without hicarbonate and carbon dioxide (medium II) reduced total extraction (TE) by 60% and k by 83%.4)Preincubation of 4,4’diisothio2,2’stilbene disulfonic acid (DIDS),an inhibitor of anion exchanye systems,in medium I similarly re= duced TE by 66%,while k was not affected.5)Inhibition of glutamine syn= thetase by 1-methionine sulfoximine reduced TE by 50% and k by 69%. The results indicate that,in addition to metabolic trapping,13N uptake in myocytes depends on intracellular buffer capacity,probably mediated by an anion exchange system in the cell membrane.