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Serum-myocardium gradients of long chain non-esterified fatty acids (NEFA) in dog, rat and man
64 ISOPROTERENOL
STIMULATES RATES OF 1,IPOLYSIS IN ISOlATEI) MYOCARDTAI. CEI.1.S FROM RA'I HEART. D.L. Severson, A. Kryski, Jr., ti. Kenno. Department of Pharmacology and Therapeutics, Faculty of Medicine, University uf Calgary, Calgarv T2Y lk4 Ccrnadn. Calcium-tolerant myocardial cells (myocytes) were isolated from the ventricles oi rat hearts by perfusion and digestion with collaxenase. l'hr viabiIity of these myocyte preparations was 75-90X (percentage of rells exclllding Trypan Blue :~nd hnvin$ .? rod-shaped morphology). Less than 10% of the myocytrs exhibited spontaneous c‘oj,tractiuns when incubated in burfers containing 1.5 mM CaCl2. Qntrs of lipolysi:: (hydrolysis of endogenous triacylglycerols) were measured by the output ti,i glycerol. The presence of glucose (11 m?l) in the incubation medium produced a Z-fold enhancement of lipolytic rates. The addition of isoproterenol (ISO) resulted in a concentration-dependent increase in glycerol output; half-masimnl stimulntiun was observed at 0.1-0.2 UN ISO. The combination of IS0 (10 IIM) plus j-isobutyl I-methv1 xanthine (100 .1X) produced a five-fold increase in glycerol olltput (from :+.7 i I.4 nmol/hr/ lo6 cells to 24.3 f 4.8 nmol/hr/lob cells; n = 5). l.ipolysis was .>lso stimulated by forskolin (0.1-100 HIM). In contrast to results with perfused hearts, IS0 produced the same fold-stimulation of lipolysis when calcium was omitted from the incubation medium. Increasing the CaC12 concentration tl, i mM did not increase basal rates of lipolysis. (Supported by the Medical Research Council of Canadd).
65 KINETICS
OF MYOCAROIAL FhTTY ACID WTAKE. J.F. Hijtter, H.I?. Piper, P.G. Spieck~ermann Zentrum Physiologic, Liniversitat GEttingen, FKG Using a computer assisted working rat heart effects of albuminand substrate corm centrations on uptake and oxidation of nonestsrified fatty acids (PJEFAJ were cvaludtea. Hearts lvers perfused with a basic medium containing 1 mfl lactate and 5 mP1 glucose. The RQ was used to measure the rate of fatty acid oxidatior. It is expressed as percentage af total oxidation. At a constant albumin concentration fatty acid oxidation was shown to increase linear ly with the NEFA concentration. At a constant NEFA/albumin-ratio, however. a saturation curve was found. Although albumin has an inhibitory effect, there is no correlation between fatty acid oxidation and unbound MFA concentrations, which were calcu These results suegest an uptake mechanism lated using stepwise equilibrium constants. mediated by an albumin receptor, by which aibumin bound l4EFA are transported into the cell. Csing this hypothesis the rate law was derived: 0x1 = 0x1~ + by] /r[fi~t3j + km), where OX1 and k are constants, It shows 8ery go#d agreement tained by other workers. Supported
66
by
the
UFG.
SFB
89
with -
@PJ our Kardiologie
and bL4 experimental
are
MEFPresults
and albumin and even
with
concentrations. data ob-
G;'ttingen
SEXJM-MYOCAfiDI~ GRAIXZNTS OF LONG CHAIN NON-%STERIlWD FATTY ACIDS (NiiFA) IN DOG, HAT AJ_ND MAN. G.J. vari der Vusse, Th.1l.M. Hoemen, W. Flameng, B.S. Reneman. Department of r'hysiology, University of Limburg, Maastricht, 'Ihe Netherlands. Although the mechanism underlying the movement of P;EFA from blood to llrart ceils has not beer1 elucidated in Great detail, diffusion is thought to be irwolved. This mechanism implies a higher co:itent of fatty acids ill the intravascular space than i:i we measured NEFA concentrations in arterial serum the myocyts. In the present study, 01' man, dog arid rat as well as the myocardial tissue coiltcnt iI: these sp*zeies by gasliquid chromatography. In the three species under investigation a gradient from serum to heart tissue for total (NEFA) could be testahlished. 'I'he ratio serum/left wntricuLar tissue iri dogs, serum/right auricular appendage in dogs, serum/whol~ heart tissue irl rats and serum/right auricular appendage in man was found to be 6.4, -!.i, 5.b and -. 8, respectively. The highest gradient was fouud for oleic acid (ranging from 1l.U to 1y.U in dogs) whereas IIO significant gradient for arachidonic acid could be detect?d. Ir. the dog the arterio-local venous differences of NEFA across the .Lcft ventricular tissue correlated better wit?] the serunl/tissuc ratio of NEFA than with the arterial NEFA level. Sirlcc the correlation coefficierlt (0.74) was still far from oxccllent, more factors than the NEFA serum-tissue gradient are likely to be involved in determining the extent of which NP:FA arr cxtractcd ty myocardial tissw.
STIMULATES RATES OF 1,IPOLYSIS IN ISOlATEI) MYOCARDTAI. CEI.1.S FROM RA'I HEART. D.L. Severson, A. Kryski, Jr., ti. Kenno. Department of Pharmacology and Therapeutics, Faculty of Medicine, University uf Calgary, Calgarv T2Y lk4 Ccrnadn. Calcium-tolerant myocardial cells (myocytes) were isolated from the ventricles oi rat hearts by perfusion and digestion with collaxenase. l'hr viabiIity of these myocyte preparations was 75-90X (percentage of rells exclllding Trypan Blue :~nd hnvin$ .? rod-shaped morphology). Less than 10% of the myocytrs exhibited spontaneous c‘oj,tractiuns when incubated in burfers containing 1.5 mM CaCl2. Qntrs of lipolysi:: (hydrolysis of endogenous triacylglycerols) were measured by the output ti,i glycerol. The presence of glucose (11 m?l) in the incubation medium produced a Z-fold enhancement of lipolytic rates. The addition of isoproterenol (ISO) resulted in a concentration-dependent increase in glycerol output; half-masimnl stimulntiun was observed at 0.1-0.2 UN ISO. The combination of IS0 (10 IIM) plus j-isobutyl I-methv1 xanthine (100 .1X) produced a five-fold increase in glycerol olltput (from :+.7 i I.4 nmol/hr/ lo6 cells to 24.3 f 4.8 nmol/hr/lob cells; n = 5). l.ipolysis was .>lso stimulated by forskolin (0.1-100 HIM). In contrast to results with perfused hearts, IS0 produced the same fold-stimulation of lipolysis when calcium was omitted from the incubation medium. Increasing the CaC12 concentration tl, i mM did not increase basal rates of lipolysis. (Supported by the Medical Research Council of Canadd).
65 KINETICS
OF MYOCAROIAL FhTTY ACID WTAKE. J.F. Hijtter, H.I?. Piper, P.G. Spieck~ermann Zentrum Physiologic, Liniversitat GEttingen, FKG Using a computer assisted working rat heart effects of albuminand substrate corm centrations on uptake and oxidation of nonestsrified fatty acids (PJEFAJ were cvaludtea. Hearts lvers perfused with a basic medium containing 1 mfl lactate and 5 mP1 glucose. The RQ was used to measure the rate of fatty acid oxidatior. It is expressed as percentage af total oxidation. At a constant albumin concentration fatty acid oxidation was shown to increase linear ly with the NEFA concentration. At a constant NEFA/albumin-ratio, however. a saturation curve was found. Although albumin has an inhibitory effect, there is no correlation between fatty acid oxidation and unbound MFA concentrations, which were calcu These results suegest an uptake mechanism lated using stepwise equilibrium constants. mediated by an albumin receptor, by which aibumin bound l4EFA are transported into the cell. Csing this hypothesis the rate law was derived: 0x1 = 0x1~ + by] /r[fi~t3j + km), where OX1 and k are constants, It shows 8ery go#d agreement tained by other workers. Supported
66
by
the
UFG.
SFB
89
with -
@PJ our Kardiologie
and bL4 experimental
are
MEFPresults
and albumin and even
with
concentrations. data ob-
G;'ttingen
SEXJM-MYOCAfiDI~ GRAIXZNTS OF LONG CHAIN NON-%STERIlWD FATTY ACIDS (NiiFA) IN DOG, HAT AJ_ND MAN. G.J. vari der Vusse, Th.1l.M. Hoemen, W. Flameng, B.S. Reneman. Department of r'hysiology, University of Limburg, Maastricht, 'Ihe Netherlands. Although the mechanism underlying the movement of P;EFA from blood to llrart ceils has not beer1 elucidated in Great detail, diffusion is thought to be irwolved. This mechanism implies a higher co:itent of fatty acids ill the intravascular space than i:i we measured NEFA concentrations in arterial serum the myocyts. In the present study, 01' man, dog arid rat as well as the myocardial tissue coiltcnt iI: these sp*zeies by gasliquid chromatography. In the three species under investigation a gradient from serum to heart tissue for total (NEFA) could be testahlished. 'I'he ratio serum/left wntricuLar tissue iri dogs, serum/right auricular appendage in dogs, serum/whol~ heart tissue irl rats and serum/right auricular appendage in man was found to be 6.4, -!.i, 5.b and -. 8, respectively. The highest gradient was fouud for oleic acid (ranging from 1l.U to 1y.U in dogs) whereas IIO significant gradient for arachidonic acid could be detect?d. Ir. the dog the arterio-local venous differences of NEFA across the .Lcft ventricular tissue correlated better wit?] the serunl/tissuc ratio of NEFA than with the arterial NEFA level. Sirlcc the correlation coefficierlt (0.74) was still far from oxccllent, more factors than the NEFA serum-tissue gradient are likely to be involved in determining the extent of which NP:FA arr cxtractcd ty myocardial tissw.