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Influence of capillary permeability on interstitial fluid composition
52
INFLUENCE
OF
H. Kammermeier, Dept. Physiology
CAPILLARY B.
PERMEABILITY
Wendtland, RWTH Aachen,
ON
E. Jingling, Forckenbeckstr.,
INTERSTITIAL G.
Stijcker D-51
FLUID
COMPOSITION
Aachen
F.R.G.
Suitable experimental setup allows to sample interstitial fluid (IF) from the SLITface of ventricles of isolated perfused rat hearts. (Pfliiqers Arch. 394:Rll (1982)). The composltion of IF differs markedly from that of arter‘ial and venous perfusate. The glucose concentration of IF is lower by UD to 406, that of pyruvate by up to 25?. The IF lactate concentration is higher by up to 400% as compard to that of venous effluent. The concentration differences between effluent and IF as well as the rate of oroduction of IF depend markedly on experimental conditions as for example duration of experiment (30 to 150 min), presence of pyruvate, hypoxia, administration of isoproterenol. The IF contains proteins in low concentrations (albumin, LDH) but no detectable CK activity. Lactate production in presence of 14C-pyruvate has its origin mainly from pyruvate. Calculated capillary permeability data indicate a marked but variable barrier function of the capillary wall and presumably a distinct metabol ic contribution of the endothel ium. Supported by DFG Ka 337/7-k.
53
CORONARY VASCULAR HARXODYNAHICS VASCULAR COMPL1ANCE.J. A. E.
DURINGLONGDIASTOLESEXPLAINED3YAN
INTRAHYOCARDIAl.
Spaan, J. D. Laird, M. I. M. Noble . Department of Physiology and Physiological Physics, University of Leiden, The Netherlands. Anaesthetised goats were subjected to constant pressure perfusion of the left main coronary artery and the great cardiac vein was cannulated. Atrio-ventricular dissociation was induced and the right ventricle paced. Long diastoles were induced by switching off the pace-maker in the presence of beta-adrenergic blockade. Coronary inflow declined during diastole at constant perfusion pressure. Coronary venous outflow increased during the long diastole and then declined. Coronary inflow this response occlusion early in diastole caused a rapid drop in perfusion pressure; These results was much slower when elicited after several seconds of cardiac arrest. were predicted by a model incorporating an intramyocardial compliance (Spaan et al, 1981, Circ. Res., 49, 584-593). This model also predicted the relationships between instantaneous perfusion pressure and coronary inflow described in the literature and attributed to variable resistances of the classical and waterEal1 type. The latter hypothesis is based on calculations of “resistance” from instantaneous pressures and flows during the pulsatile cardiac cycle.
54
ATRIAL NATRIURETIC FACTOR, PL:RIFICATION, ACTION ON BLOOD VESSELS AND POSSIBLE MECHANISM OF ACTION. M. Cantin, R. Garcia, 6. Thihault, P. Hamet and J. &nest. Clinical Research Institute of Montreal, Montreal, Canada. We have previously shown that atria1 specific granules possess a potent diuretic and natriuretic effect (Experientia 3:1071, 19X2). After a series of chromatographic steps, the specific activity of the atria1 natriuretic factor was increased from 193 (in atria1 homogenates) to 242,000, representing a 1250-fold purification. Ten picoThe actimoles of this material increased natriur‘esis in the bioassay rat by 1009. vity is completely abolished after incubation with several proteases suggesting that it is a polypeptide with a molecular weight of about 4000. This factor does not inhibit the activity of Na-R ATPase but the natriuresis is accompanied hv a 2%fold increase in urinary cGMP excretion without changes in cAb!F’ and a 4-fold increase in plasma cGMP. Study of the ratio of cvclic nucleotide clearance over that of rreatini ANF ne suggests a net tubular secretion of cC,MP (increase of ratio of 1.1 to 2.7). also increased the cGMP level vitro either in kidney minces or in primary cultures --in __ of renal tubular cells. ANF produced a potent relaxant effect on arterial strips (aorta and mesenteric artery) previously contracted by norcpinephrine (NE). After Similar effects the initial application of AhT, NE did not contract the arteries. were observed in the perfused rat mesenteric artery. These results suggest that RNF may act through cGMP
INFLUENCE
OF
H. Kammermeier, Dept. Physiology
CAPILLARY B.
PERMEABILITY
Wendtland, RWTH Aachen,
ON
E. Jingling, Forckenbeckstr.,
INTERSTITIAL G.
Stijcker D-51
FLUID
COMPOSITION
Aachen
F.R.G.
Suitable experimental setup allows to sample interstitial fluid (IF) from the SLITface of ventricles of isolated perfused rat hearts. (Pfliiqers Arch. 394:Rll (1982)). The composltion of IF differs markedly from that of arter‘ial and venous perfusate. The glucose concentration of IF is lower by UD to 406, that of pyruvate by up to 25?. The IF lactate concentration is higher by up to 400% as compard to that of venous effluent. The concentration differences between effluent and IF as well as the rate of oroduction of IF depend markedly on experimental conditions as for example duration of experiment (30 to 150 min), presence of pyruvate, hypoxia, administration of isoproterenol. The IF contains proteins in low concentrations (albumin, LDH) but no detectable CK activity. Lactate production in presence of 14C-pyruvate has its origin mainly from pyruvate. Calculated capillary permeability data indicate a marked but variable barrier function of the capillary wall and presumably a distinct metabol ic contribution of the endothel ium. Supported by DFG Ka 337/7-k.
53
CORONARY VASCULAR HARXODYNAHICS VASCULAR COMPL1ANCE.J. A. E.
DURINGLONGDIASTOLESEXPLAINED3YAN
INTRAHYOCARDIAl.
Spaan, J. D. Laird, M. I. M. Noble . Department of Physiology and Physiological Physics, University of Leiden, The Netherlands. Anaesthetised goats were subjected to constant pressure perfusion of the left main coronary artery and the great cardiac vein was cannulated. Atrio-ventricular dissociation was induced and the right ventricle paced. Long diastoles were induced by switching off the pace-maker in the presence of beta-adrenergic blockade. Coronary inflow declined during diastole at constant perfusion pressure. Coronary venous outflow increased during the long diastole and then declined. Coronary inflow this response occlusion early in diastole caused a rapid drop in perfusion pressure; These results was much slower when elicited after several seconds of cardiac arrest. were predicted by a model incorporating an intramyocardial compliance (Spaan et al, 1981, Circ. Res., 49, 584-593). This model also predicted the relationships between instantaneous perfusion pressure and coronary inflow described in the literature and attributed to variable resistances of the classical and waterEal1 type. The latter hypothesis is based on calculations of “resistance” from instantaneous pressures and flows during the pulsatile cardiac cycle.
54
ATRIAL NATRIURETIC FACTOR, PL:RIFICATION, ACTION ON BLOOD VESSELS AND POSSIBLE MECHANISM OF ACTION. M. Cantin, R. Garcia, 6. Thihault, P. Hamet and J. &nest. Clinical Research Institute of Montreal, Montreal, Canada. We have previously shown that atria1 specific granules possess a potent diuretic and natriuretic effect (Experientia 3:1071, 19X2). After a series of chromatographic steps, the specific activity of the atria1 natriuretic factor was increased from 193 (in atria1 homogenates) to 242,000, representing a 1250-fold purification. Ten picoThe actimoles of this material increased natriur‘esis in the bioassay rat by 1009. vity is completely abolished after incubation with several proteases suggesting that it is a polypeptide with a molecular weight of about 4000. This factor does not inhibit the activity of Na-R ATPase but the natriuresis is accompanied hv a 2%fold increase in urinary cGMP excretion without changes in cAb!F’ and a 4-fold increase in plasma cGMP. Study of the ratio of cvclic nucleotide clearance over that of rreatini ANF ne suggests a net tubular secretion of cC,MP (increase of ratio of 1.1 to 2.7). also increased the cGMP level vitro either in kidney minces or in primary cultures --in __ of renal tubular cells. ANF produced a potent relaxant effect on arterial strips (aorta and mesenteric artery) previously contracted by norcpinephrine (NE). After Similar effects the initial application of AhT, NE did not contract the arteries. were observed in the perfused rat mesenteric artery. These results suggest that RNF may act through cGMP