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Relation between intracellular calcium and pH on the contractility of newborn rats cardiac cell culture
J Mel (Xl
Cardiol 23 (Supplement
IV) (1991)
145 CARDIAC
CRYOSURGERY : CONTRIBUTION ON CRYOLESION SIZE AND DEPTH. B. Peiffert, T. Hubert. CHRUNancy,
J.P. Villemot.
Department
of Cardiac - France
54500VANDOEUVRE
and -
OF MYOCARDIAL P.M.
Mertks,
Cardio-Thoracic
TEMPERATURE
G. Pinelk
J.P. Carteaux.
Transplantation
Surgery.
Cryothermic ablation of myocardium and ortions of the specialized cardiac conduction tissues is a useful tool in the surgical treatment o P cardiac arrhythmias. The present study was designed to recise the effect of myocardial temperature for both cryolesion size and depth. F1.Pteen pigs were subjected to cardio ulmonary bypass, and standard cryothermic exposure (8 mm cryoprobe, - 80°C for 120 secondsli were used to create 3 cryolesions on the left ventricular free wall in each pig : one at a septal temperature of 37T, one at 28°C and one at 10°C. The dimensions and volumes of cryolesions created at myocardial temperatures of 3T, 28” and 10°C were compared. Cryolesions created at 10°C with the igs under h o!hermic cardiople+i;;~s were sigmficantly larger (p c 401) and deeper (p < 0,l 1) than cryoYpeslons created at 3 in the perfused beating heart. Lesion diameter, however, was not very influenced by myocardiai temperature. We conclude that cryothermia will be used after cardioplegic cardiac arrest in procedures requiring ablation of regions deep below the epicardial or endocardial surface.
146
31P NMR SPECTROSCOPY
AND MYCXXRDIAL
CONSERVATION.
PREDICTIVE
VALUE
?. G. Piilli,
P.M. Mertes.J.P. Ca~Ieaux.
J.M. Escanye. Th. Hubert, B. Wiedenkeller, J.P. Villemot. Laboratoire Chirurgie Expkrimentale Facultk de Medecine - 54505 VANWEUVRE The aim of this study was to fmd a correlation between the MRS date during the conservation phase and the haemodymxnic performance of the left ventricle after reperfusion. Seventeen pig hearts have been excised ltta cold cardioplegy (St. Thomas’ Hospital solution). The duration of conservation (storage in physiological serum at 4F) varied between 3 and 12 hours. During this conservation phase, and without removing the heart from its wntainer. the variations of pH. adenosine triphosphate (ATP) and tissue phosphocreatine (PC?) have been measured by MRS. The blood repertk ion has been effected with the aid of an isolated supported heart model. working in isavolumic conditions (LEVDP 10 mmHg). The left ver~triculer heemodynemic performance (LVP). evaluated by the peak of systolic ventrkxcular pressure (Gan) and by (dP/dthuv has been studied over a period of three hours. No correlation has been observed belween ATP. PCr and pH measured it the beginning of conservation and the LVP. However. pH and PCr measured
at the end of conservation. have been observed to be correkled 60 min Reperf. 90 min Reperf. (dJ’/~~M,x pMax (dP/dt)Max PM= r=0.71 1~0.61 K0.73 r=0.77 PH
min of reperfusion.
p=o.o04 r=0.7 1
Per
p=o.o04 In conclusion. indices
147
p=o.oz
p=O.OM
p=o.ooz
~0.65 p=o.o2
GO.66 p=o.o2
r=0.80
the pH and PCr of preserved
to PM= and (dP/dt)M=, measured 180 min Reperf. pMax (dP/d+,.fax
p=O.ool
heert. melsexed
NS
NS
NS
NS
et the end of the wnservation
period,
after either 60 or 90
seem te be predictive
of the 1eR ventricular haemodynamic performance at the onset of reperfusion.
RELATION NEWBORN
BETWEEN INTRACELLULAR RATS CARDIAC CELL CULTURE.
N. PLATONOFF ; F. JACQUEY MEDECINE EXPERIMENTALE,
CALCIUM
AND
; J.C. BERNENGO ; I. P. MAURAT. UNIVERSITE DE FRANCHE-COMTE.
PH ON THE
CONTRACTILITY
LABORATOIRES
DE GBM
OF ET
DE
The internal calcium concentration ([Cali) and the intracellular pH @Hi) have been measured on newborn rats cardiac myocytes with a micro-spectrofluorimeter. The two fluororescent indicators used are indo I/AM for [Cali and BCECF/AM for PHI evaluation. The cellular contractility was evaluated with a contractometer (LSCI. BIO-LOGIC). An increase in external calcium from 0.6 mM to 2 mM triggered a classical positive inotropic effect followed by a light increase in the free internal calcium (150 nM to 250 nM) without arty pHi variation. When the external calcium concentration ([Cal,) was increased above 2 mM, the positive inotropic effect decreased although [Cali was still increasing to high values (z-400 nh4) ; the cellular contractility was then smaller than the control. At the same time. ,,,, <:..,,,. ..( I, II3 .<.,.,. I,. the inuaicliuldr ILICLI~I,I .(L.&) l,u<.,\ll;. :ii ,, I .I.\ positive inotropic effect is explained by a more important ATPasique activity of the myofilaments. In calcium overload and an acidosis occur implying an alteration the case of high [Calo, an intraceIlular of cellular inotropism. The underlying mechanisms are still under investigation. However our results clearly demonstrate the relation between the [Cali and the pHi. We can then suggest that the pHi depends at least partly on the calcium intracellular regulation mechanism. 5.49
Cardiol 23 (Supplement
IV) (1991)
145 CARDIAC
CRYOSURGERY : CONTRIBUTION ON CRYOLESION SIZE AND DEPTH. B. Peiffert, T. Hubert. CHRUNancy,
J.P. Villemot.
Department
of Cardiac - France
54500VANDOEUVRE
and -
OF MYOCARDIAL P.M.
Mertks,
Cardio-Thoracic
TEMPERATURE
G. Pinelk
J.P. Carteaux.
Transplantation
Surgery.
Cryothermic ablation of myocardium and ortions of the specialized cardiac conduction tissues is a useful tool in the surgical treatment o P cardiac arrhythmias. The present study was designed to recise the effect of myocardial temperature for both cryolesion size and depth. F1.Pteen pigs were subjected to cardio ulmonary bypass, and standard cryothermic exposure (8 mm cryoprobe, - 80°C for 120 secondsli were used to create 3 cryolesions on the left ventricular free wall in each pig : one at a septal temperature of 37T, one at 28°C and one at 10°C. The dimensions and volumes of cryolesions created at myocardial temperatures of 3T, 28” and 10°C were compared. Cryolesions created at 10°C with the igs under h o!hermic cardiople+i;;~s were sigmficantly larger (p c 401) and deeper (p < 0,l 1) than cryoYpeslons created at 3 in the perfused beating heart. Lesion diameter, however, was not very influenced by myocardiai temperature. We conclude that cryothermia will be used after cardioplegic cardiac arrest in procedures requiring ablation of regions deep below the epicardial or endocardial surface.
146
31P NMR SPECTROSCOPY
AND MYCXXRDIAL
CONSERVATION.
PREDICTIVE
VALUE
?. G. Piilli,
P.M. Mertes.J.P. Ca~Ieaux.
J.M. Escanye. Th. Hubert, B. Wiedenkeller, J.P. Villemot. Laboratoire Chirurgie Expkrimentale Facultk de Medecine - 54505 VANWEUVRE The aim of this study was to fmd a correlation between the MRS date during the conservation phase and the haemodymxnic performance of the left ventricle after reperfusion. Seventeen pig hearts have been excised ltta cold cardioplegy (St. Thomas’ Hospital solution). The duration of conservation (storage in physiological serum at 4F) varied between 3 and 12 hours. During this conservation phase, and without removing the heart from its wntainer. the variations of pH. adenosine triphosphate (ATP) and tissue phosphocreatine (PC?) have been measured by MRS. The blood repertk ion has been effected with the aid of an isolated supported heart model. working in isavolumic conditions (LEVDP 10 mmHg). The left ver~triculer heemodynemic performance (LVP). evaluated by the peak of systolic ventrkxcular pressure (Gan) and by (dP/dthuv has been studied over a period of three hours. No correlation has been observed belween ATP. PCr and pH measured it the beginning of conservation and the LVP. However. pH and PCr measured
at the end of conservation. have been observed to be correkled 60 min Reperf. 90 min Reperf. (dJ’/~~M,x pMax (dP/dt)Max PM= r=0.71 1~0.61 K0.73 r=0.77 PH
min of reperfusion.
p=o.o04 r=0.7 1
Per
p=o.o04 In conclusion. indices
147
p=o.oz
p=O.OM
p=o.ooz
~0.65 p=o.o2
GO.66 p=o.o2
r=0.80
the pH and PCr of preserved
to PM= and (dP/dt)M=, measured 180 min Reperf. pMax (dP/d+,.fax
p=O.ool
heert. melsexed
NS
NS
NS
NS
et the end of the wnservation
period,
after either 60 or 90
seem te be predictive
of the 1eR ventricular haemodynamic performance at the onset of reperfusion.
RELATION NEWBORN
BETWEEN INTRACELLULAR RATS CARDIAC CELL CULTURE.
N. PLATONOFF ; F. JACQUEY MEDECINE EXPERIMENTALE,
CALCIUM
AND
; J.C. BERNENGO ; I. P. MAURAT. UNIVERSITE DE FRANCHE-COMTE.
PH ON THE
CONTRACTILITY
LABORATOIRES
DE GBM
OF ET
DE
The internal calcium concentration ([Cali) and the intracellular pH @Hi) have been measured on newborn rats cardiac myocytes with a micro-spectrofluorimeter. The two fluororescent indicators used are indo I/AM for [Cali and BCECF/AM for PHI evaluation. The cellular contractility was evaluated with a contractometer (LSCI. BIO-LOGIC). An increase in external calcium from 0.6 mM to 2 mM triggered a classical positive inotropic effect followed by a light increase in the free internal calcium (150 nM to 250 nM) without arty pHi variation. When the external calcium concentration ([Cal,) was increased above 2 mM, the positive inotropic effect decreased although [Cali was still increasing to high values (z-400 nh4) ; the cellular contractility was then smaller than the control. At the same time. ,,,, <:..,,,. ..( I, II3 .<.,.,. I,. the inuaicliuldr ILICLI~I,I .(L.&) l,u<.,\ll;. :ii ,, I .I.\ positive inotropic effect is explained by a more important ATPasique activity of the myofilaments. In calcium overload and an acidosis occur implying an alteration the case of high [Calo, an intraceIlular of cellular inotropism. The underlying mechanisms are still under investigation. However our results clearly demonstrate the relation between the [Cali and the pHi. We can then suggest that the pHi depends at least partly on the calcium intracellular regulation mechanism. 5.49