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Vasodilation to nerve stimulation in portal hypertension: Role of nitric oxide and calcitonin gene-related peptide
HEPATOLOGY VoL 22, No. 4, Pt. 2, 1995
601 P E R I P H E R A L E N D O T O X E M I A AND H Y P E R D Y N A M I C
602
C I R C U L A T I O N OF RATS W I T H E X T R A H E P A T I C OR I N T R A H E P A T I C P O R T A L HYPERTENSION. FY Lee. SS Wang. MCM Yang*. YT Tsai. SL Wu. RH Lu. CY Chan. SD Lee. Div. of Gastroenterology, Dept. of Medicine, and *Dept. of Medical Education and Research, Veterans General Hospital-Taipei and National Yang-Ming University School of Medicine, Taipei, Taiwan, R.O,C. The physiologic similarities between cirrhotic and septic patients have implicated peripheral endotoxcmia as a possible mediator of the hemodynamic changes observed in patients with liver cirrhosis. This study investigated the role of peripheral endotoxemia in the development of hypcrdynamic circulation observed in rats with extrahepatic (high collatcralization) or intrahepatic (low collateralization) portal hypertension. In addition, using the two portal hypertensive rat models, we studied the role of collateral circulation in the development of cndotoxcmia in experimental portal hypertension. As compared with sham-operated rats, decreased mean arterial pressure and systemic vascular resistance were detected on day 1, day 4, and day 14 following partial portal vein ligation. By day 1, the cardiac index of portal veinligated rats was similar to that of sham-operated rats, and progressively increased, thereafter, reaching statistically higher values on day 4 and day 14. No differences were observed in the plasma cndotoxin levels between portal vein-ligatud and sham-operated rats throughout the observation period. Both carbon tetrachloride-induced cirrhotic rats with and without ascites had a higher cardiac index and lower systemic vascular resistance than those of control rats, and cirrhotic rats with ascites had the lowest systemic vascular resistance. Plasma endotoxin levels were higher in cirrhotic rats with ascites (8.6+2.0 pg/ml, p<0.01) than those of control rats (2.2~-0.3 pg/ml) and cirrhotic rats without ascitcs (2.4+0.6 pg/ml). These results suggest that factors other than peripheral cndotoxcmia play a role in the development of hypcrdynamic circulation observed in rats with extrahepatic portal hypertension and cirrhotic rats without ascites, but peripheral endotoxemia may contribute to the maintenance of hyperdynamic circulation found in cirrhotic rats with ascites. The severity of liver disease may be a more important factor than the presence of porto-systemic shunting for the development of endotoxemia in portal hypertensive states.
603
257A
AASLD ABSTRACTS
VASODILATION TO NERVE STIMULATION IN PORTAL HYPERTENSION: ROLE OF NITRIC OXIDE AND CALCITONIN GENE-RELATED PEPTIDE L,T, Sumanovski. C. Kaufmann. G.A. Stalder. C.C. Siebir, Div. of Gastroenterology and Research, University Hospital Basel, Switzerland. Pedal hypertension goes along with a vascular hyporeactivity and a vasedilation, reversed by inhibiting nitric oxide (NO) biosynthesis. NO and calcitonin gene-related peptide (CGRP) are neurotransmitters of non-adrenerglc non-cholinergic (NANC) nerves. The role of NO and CGRP upon nerve-stimulated vasedilation in portal hypertension is unknown. Here, we tested, 1) if in vitro peffused preparations of portal hypertensive rats (induced by padial portal vein ligation, PVL) display increased vasodilation to periaderial nerve stimulation (PNS) compared to normal controls (NOR) and, 2) if this vasodUation is modulated by NO and CGRP. Methqds. Superior mesenteric arteries of male Sprague-Dawley rats was cannulated, the vascular bed isolated and perfused (4ml.min "1) with oxygenated 37oc Krebs solution. Pressure was measured by a pressure transducer and registered on a polygraph, Vasedilatory responses were determined to PNS (10V,lms) with increasing amounts of Hertz using a nerve stimulator after a preconstrictlon with methoxamine and guanethidine (both 5x10"5M), The role of NO was tested by preincubation with the NOformation antagonist N(°-Nitro-L-Arginine (NNA, 10"4M), and of CGRP with the antagonist CGRP8-37 (10"7M). Results. Percentage changes (%) compared to basal (100%). UI ~aired Student's t-test.' )<0,05 PVL con" ~ared to NOR. Hertz 2 4 8 12 PVL (N=7) 82.8_+2.9* 66,0_+2.6* 55,1_+3.6" 57.0-+2.9 ° NOR (N=8) 91.4-+1.8 78.4+3.6 67:7_+3.6 68.7_+2.9 PVL+NNA (N=6) 83.3-+1,4 72.3-+2.2 62.2_+3.3 64.7+2.1 NOR+NNA (N=6) 89,1+3.6 75.9+4.7 71.3-+4.8 70.2_+5.0 PVL+CGRP8-37 96.4_+2.6 84.1-+2.4 72~2-+4.2 76.9-+2.3 (N=4/ NOR+CGRP8-37 92.3-+3.8 85,8_+1.6 74.9+2.8 80.3-+3.9 (N=4) Vasodilation to PNS was significantly (*) more pronounced in preparations of PVL rats and reversed by inhibiting NO and CGRP activity. Summary. 1) Vessel preparations of PVL rats display a significantly enhanced vasedilaticn to PNS. 2) This increased vasodilation is reversed by inhibiting NANCneurotransmitters. Conclusions. 1) Nerve-mediated vasedilation is involved in the increased vasodilatory activity under portal hypertension. 2) This increased nerve-mediated vasodilation seems caused by the NANCneurotransmitters NO and CGRP,
VARX~-v- -v-~m~1~JG OR ~ aBCITCg: NO DIIF]~JCIICZS IS PQ~LT3EL IBRIOD3Bm~K~CS. K Hal=. M Roesele, A 0chs. S LU* I P Oe~beE~, V a i ~ I E l t l ~ l r , ~ nl~ Blue. Dept. of Medicine, University Hospital Preibuz~, Germany and *Dept. of Surgery, University Hospit&l of Wes¢ China ffniversity of Medical Sclaucen, Chengdu, China. Typical ¢omplic&~icn= of patients with advanced liver cirrhosis are ~¢ul'~ent vlri=eal bleeding (VB) and refractory ascitee (RA}. As we ¢lid ~he obeervanion ~-hat the gEome majority of RA patients had no episodes of varic,al bleedlng, wa evaluated cud compared pcc~cal hemodynam~cs in patients ~rlth oompllcatad portal hypertension. The st~t~y was perfoz~md in 367 consecutive patients awaiting the i~=plcu~a~ion of a t=ansjug~lar intrahepe=io portosystemlo s~an~-shunt (TZPS) for recuxTent variceal bleeding (n-296) or rsfEactoz-f aaoitas (n=71; aec-~m crea~inina < 2.0 m~/~l). Portal pressure (PP}, central venous pressure (CVP} and pcrtosyat==io p r e s s u r e gradient (PSPG} were measured ¢L~rac~iy during the TIPS procedure Ice ~0] whi~x was p~foz~le~ ~IChou~ g e n ~ ~nes~heeia. PozCal and splenic flow data w~=e de~ermine~! by dupleo¢ sonogTaphy (tTltr-~-w~ 9, ATL) wiP.hin one week b e f o r e T I P S . ~.llulta~. The ~ and t h e ~ g'~otll~l .44d oct ~J~'FI~ le4--th real oeot 1:O seX. or etiology of cirrhosis. RA patients were signlflcan~ly olde¢~ ~han VB patients (56.~±9.1 versus 52.S±12.0 yeses, mecu±SD, p
(RA: 8.6±5.5;
VB=.'7.9i-4.5},
and PS]~G (R&: 31.2:1:S.7; VB=
30.6~6.6) dLi~ = o ~ d L i f f e r aig=ificantly between the ~ o ~ o u p a ~ s p i t a pn=len~s" Childopugh'e ¢laaa had. llama effects on PP and. PSPG (p<0.0S} ~ Poz~al ~ 4 " . . . . ~ . flow velocity Jim/a] and b l o o ~ flow ~ll/=~J~] w~re only slightly lower (p>0.2) in RA {13.8±7.8; 710~430) ~han in VB pa~ienus (15.3+9.9; 7S0±510). No ~ifferon=ea were found in splenic vein f l ~ . Conoluslon: The type of oo=plioation, i.e. varioaal bleeding Or refractory aaoi~ea, in patienns with severe portal hyperuension canno~ be easily explained by portal hemody~=m4~s (portal blood flow, portal prealRtre, portosys~emic pressure gra~Lient, appa=en~ portal vaac~41a~ resistance). Despite ~he evidence of portal hypertension on aacitss g~neration o t h e r factors (renal, hepatic, humeral) a a ~ to be essential f o r t h e fo~=atio~ Of refractory ascitea.
604
RESTING VASODILATORY CAPACITY IN RATS WITH CIRRHOSIS. V Safka. R Moreau. A Gadano. O Labrec. INSERM U-24, h6pital Beaujon, Cllchy, France. The hyperdynamic cimulation observed in cirrhosis may be due to an increased production of endogenous vasodilators. The aim of this study was to assess the rote of 3 mechanisms of the vasorelaxant pathway. The effects of nlcardipine, verapamil and diltiazem, 3 calcium antagonists; nitric oxide (NO) and pmstacyclin (PGI2), 2 endogenous vasodilators acting on 2 second messenger systems (cGMP and cAMP) and aprikalim opening K+ ATP dependent channels, were compared on adedal pressure and heart rate in bile duct tigated and control rats using dose response curves. In all groups of cirrhotic rats, arlefial pressure was significantly lower than in controls. The decease in arterial pressure (delta pressure) with nicardipine (0.02 to 2 mg/kg) was significantly greater in control (40~5 mmHg) than in cirrhotic (32+10 mmHg) rats, but the values for aderial pressure at the maximal dose were not significantly different. The negative chronotroplc effects of nicardipine were mare marked in cirrhotic than in control rats. Verapamil (0.02 to 0.4 mg/kg min) had similar effects on adedal pressure in both groups, but also had greater chronotropic effects in cirrhotic animals. Diltiazem (0.5 to 10 mg/kg) reduced more aderial pressure in normal (37+8 mmHg) than in cirrhotic (29-+5 mmHg) rats; the values for arterial pressure at the maximal doses were not significantly different. The effects of sodium nitreprusside (5 to 120 p.g/kg), a NO donor and PGI 2 (0.5 to 20 p.g/kg) on arterial pressure were less marked in cirrhosis (25-+2 mmHg and 27+6 mmHg, respectively) than in normal rats (37_+6 mmHg and 34+_6 mmHg, respectively}. Following nitroprusside administration, the values for adedal pressure at the maximal dose were significantly higher in cirrhotic rats (78_+7mmHg) than in normal rats (72_+4mmHg). The effects of aprikalim (10 to 800 pg(kg) on arterial pressure were also less marked in cirrhosis (36-+1 mmHg) than in normal rats ((43_+4 mmHg). The values for adedal pressure at the maximal dose were not significantly different. In conclusion, this study shows that systemic vasodilatation mainly depends on an hyperproduction of endogenous vasodilators acting on second messenger systems but not on endogenous calcium antagonists. Moreover, it suggests that calcium and K + ATP channels have a normal response to vasodilator substances.
601 P E R I P H E R A L E N D O T O X E M I A AND H Y P E R D Y N A M I C
602
C I R C U L A T I O N OF RATS W I T H E X T R A H E P A T I C OR I N T R A H E P A T I C P O R T A L HYPERTENSION. FY Lee. SS Wang. MCM Yang*. YT Tsai. SL Wu. RH Lu. CY Chan. SD Lee. Div. of Gastroenterology, Dept. of Medicine, and *Dept. of Medical Education and Research, Veterans General Hospital-Taipei and National Yang-Ming University School of Medicine, Taipei, Taiwan, R.O,C. The physiologic similarities between cirrhotic and septic patients have implicated peripheral endotoxcmia as a possible mediator of the hemodynamic changes observed in patients with liver cirrhosis. This study investigated the role of peripheral endotoxemia in the development of hypcrdynamic circulation observed in rats with extrahepatic (high collatcralization) or intrahepatic (low collateralization) portal hypertension. In addition, using the two portal hypertensive rat models, we studied the role of collateral circulation in the development of cndotoxcmia in experimental portal hypertension. As compared with sham-operated rats, decreased mean arterial pressure and systemic vascular resistance were detected on day 1, day 4, and day 14 following partial portal vein ligation. By day 1, the cardiac index of portal veinligated rats was similar to that of sham-operated rats, and progressively increased, thereafter, reaching statistically higher values on day 4 and day 14. No differences were observed in the plasma cndotoxin levels between portal vein-ligatud and sham-operated rats throughout the observation period. Both carbon tetrachloride-induced cirrhotic rats with and without ascites had a higher cardiac index and lower systemic vascular resistance than those of control rats, and cirrhotic rats with ascites had the lowest systemic vascular resistance. Plasma endotoxin levels were higher in cirrhotic rats with ascites (8.6+2.0 pg/ml, p<0.01) than those of control rats (2.2~-0.3 pg/ml) and cirrhotic rats without ascitcs (2.4+0.6 pg/ml). These results suggest that factors other than peripheral cndotoxcmia play a role in the development of hypcrdynamic circulation observed in rats with extrahepatic portal hypertension and cirrhotic rats without ascites, but peripheral endotoxemia may contribute to the maintenance of hyperdynamic circulation found in cirrhotic rats with ascites. The severity of liver disease may be a more important factor than the presence of porto-systemic shunting for the development of endotoxemia in portal hypertensive states.
603
257A
AASLD ABSTRACTS
VASODILATION TO NERVE STIMULATION IN PORTAL HYPERTENSION: ROLE OF NITRIC OXIDE AND CALCITONIN GENE-RELATED PEPTIDE L,T, Sumanovski. C. Kaufmann. G.A. Stalder. C.C. Siebir, Div. of Gastroenterology and Research, University Hospital Basel, Switzerland. Pedal hypertension goes along with a vascular hyporeactivity and a vasedilation, reversed by inhibiting nitric oxide (NO) biosynthesis. NO and calcitonin gene-related peptide (CGRP) are neurotransmitters of non-adrenerglc non-cholinergic (NANC) nerves. The role of NO and CGRP upon nerve-stimulated vasedilation in portal hypertension is unknown. Here, we tested, 1) if in vitro peffused preparations of portal hypertensive rats (induced by padial portal vein ligation, PVL) display increased vasodilation to periaderial nerve stimulation (PNS) compared to normal controls (NOR) and, 2) if this vasodUation is modulated by NO and CGRP. Methqds. Superior mesenteric arteries of male Sprague-Dawley rats was cannulated, the vascular bed isolated and perfused (4ml.min "1) with oxygenated 37oc Krebs solution. Pressure was measured by a pressure transducer and registered on a polygraph, Vasedilatory responses were determined to PNS (10V,lms) with increasing amounts of Hertz using a nerve stimulator after a preconstrictlon with methoxamine and guanethidine (both 5x10"5M), The role of NO was tested by preincubation with the NOformation antagonist N(°-Nitro-L-Arginine (NNA, 10"4M), and of CGRP with the antagonist CGRP8-37 (10"7M). Results. Percentage changes (%) compared to basal (100%). UI ~aired Student's t-test.' )<0,05 PVL con" ~ared to NOR. Hertz 2 4 8 12 PVL (N=7) 82.8_+2.9* 66,0_+2.6* 55,1_+3.6" 57.0-+2.9 ° NOR (N=8) 91.4-+1.8 78.4+3.6 67:7_+3.6 68.7_+2.9 PVL+NNA (N=6) 83.3-+1,4 72.3-+2.2 62.2_+3.3 64.7+2.1 NOR+NNA (N=6) 89,1+3.6 75.9+4.7 71.3-+4.8 70.2_+5.0 PVL+CGRP8-37 96.4_+2.6 84.1-+2.4 72~2-+4.2 76.9-+2.3 (N=4/ NOR+CGRP8-37 92.3-+3.8 85,8_+1.6 74.9+2.8 80.3-+3.9 (N=4) Vasodilation to PNS was significantly (*) more pronounced in preparations of PVL rats and reversed by inhibiting NO and CGRP activity. Summary. 1) Vessel preparations of PVL rats display a significantly enhanced vasedilaticn to PNS. 2) This increased vasodilation is reversed by inhibiting NANCneurotransmitters. Conclusions. 1) Nerve-mediated vasedilation is involved in the increased vasodilatory activity under portal hypertension. 2) This increased nerve-mediated vasodilation seems caused by the NANCneurotransmitters NO and CGRP,
VARX~-v- -v-~m~1~JG OR ~ aBCITCg: NO DIIF]~JCIICZS IS PQ~LT3EL IBRIOD3Bm~K~CS. K Hal=. M Roesele, A 0chs. S LU* I P Oe~beE~, V a i ~ I E l t l ~ l r , ~ nl~ Blue. Dept. of Medicine, University Hospital Preibuz~, Germany and *Dept. of Surgery, University Hospit&l of Wes¢ China ffniversity of Medical Sclaucen, Chengdu, China. Typical ¢omplic&~icn= of patients with advanced liver cirrhosis are ~¢ul'~ent vlri=eal bleeding (VB) and refractory ascitee (RA}. As we ¢lid ~he obeervanion ~-hat the gEome majority of RA patients had no episodes of varic,al bleedlng, wa evaluated cud compared pcc~cal hemodynam~cs in patients ~rlth oompllcatad portal hypertension. The st~t~y was perfoz~md in 367 consecutive patients awaiting the i~=plcu~a~ion of a t=ansjug~lar intrahepe=io portosystemlo s~an~-shunt (TZPS) for recuxTent variceal bleeding (n-296) or rsfEactoz-f aaoitas (n=71; aec-~m crea~inina < 2.0 m~/~l). Portal pressure (PP}, central venous pressure (CVP} and pcrtosyat==io p r e s s u r e gradient (PSPG} were measured ¢L~rac~iy during the TIPS procedure Ice ~0] whi~x was p~foz~le~ ~IChou~ g e n ~ ~nes~heeia. PozCal and splenic flow data w~=e de~ermine~! by dupleo¢ sonogTaphy (tTltr-~-w~ 9, ATL) wiP.hin one week b e f o r e T I P S . ~.llulta~. The ~ and t h e ~ g'~otll~l .44d oct ~J~'FI~ le4--th real oeot 1:O seX. or etiology of cirrhosis. RA patients were signlflcan~ly olde¢~ ~han VB patients (56.~±9.1 versus 52.S±12.0 yeses, mecu±SD, p
(RA: 8.6±5.5;
VB=.'7.9i-4.5},
and PS]~G (R&: 31.2:1:S.7; VB=
30.6~6.6) dLi~ = o ~ d L i f f e r aig=ificantly between the ~ o ~ o u p a ~ s p i t a pn=len~s" Childopugh'e ¢laaa had. llama effects on PP and. PSPG (p<0.0S} ~ Poz~al ~ 4 " . . . . ~ . flow velocity Jim/a] and b l o o ~ flow ~ll/=~J~] w~re only slightly lower (p>0.2) in RA {13.8±7.8; 710~430) ~han in VB pa~ienus (15.3+9.9; 7S0±510). No ~ifferon=ea were found in splenic vein f l ~ . Conoluslon: The type of oo=plioation, i.e. varioaal bleeding Or refractory aaoi~ea, in patienns with severe portal hyperuension canno~ be easily explained by portal hemody~=m4~s (portal blood flow, portal prealRtre, portosys~emic pressure gra~Lient, appa=en~ portal vaac~41a~ resistance). Despite ~he evidence of portal hypertension on aacitss g~neration o t h e r factors (renal, hepatic, humeral) a a ~ to be essential f o r t h e fo~=atio~ Of refractory ascitea.
604
RESTING VASODILATORY CAPACITY IN RATS WITH CIRRHOSIS. V Safka. R Moreau. A Gadano. O Labrec. INSERM U-24, h6pital Beaujon, Cllchy, France. The hyperdynamic cimulation observed in cirrhosis may be due to an increased production of endogenous vasodilators. The aim of this study was to assess the rote of 3 mechanisms of the vasorelaxant pathway. The effects of nlcardipine, verapamil and diltiazem, 3 calcium antagonists; nitric oxide (NO) and pmstacyclin (PGI2), 2 endogenous vasodilators acting on 2 second messenger systems (cGMP and cAMP) and aprikalim opening K+ ATP dependent channels, were compared on adedal pressure and heart rate in bile duct tigated and control rats using dose response curves. In all groups of cirrhotic rats, arlefial pressure was significantly lower than in controls. The decease in arterial pressure (delta pressure) with nicardipine (0.02 to 2 mg/kg) was significantly greater in control (40~5 mmHg) than in cirrhotic (32+10 mmHg) rats, but the values for aderial pressure at the maximal dose were not significantly different. The negative chronotroplc effects of nicardipine were mare marked in cirrhotic than in control rats. Verapamil (0.02 to 0.4 mg/kg min) had similar effects on adedal pressure in both groups, but also had greater chronotropic effects in cirrhotic animals. Diltiazem (0.5 to 10 mg/kg) reduced more aderial pressure in normal (37+8 mmHg) than in cirrhotic (29-+5 mmHg) rats; the values for arterial pressure at the maximal doses were not significantly different. The effects of sodium nitreprusside (5 to 120 p.g/kg), a NO donor and PGI 2 (0.5 to 20 p.g/kg) on arterial pressure were less marked in cirrhosis (25-+2 mmHg and 27+6 mmHg, respectively) than in normal rats (37_+6 mmHg and 34+_6 mmHg, respectively}. Following nitroprusside administration, the values for adedal pressure at the maximal dose were significantly higher in cirrhotic rats (78_+7mmHg) than in normal rats (72_+4mmHg). The effects of aprikalim (10 to 800 pg(kg) on arterial pressure were also less marked in cirrhosis (36-+1 mmHg) than in normal rats ((43_+4 mmHg). The values for adedal pressure at the maximal dose were not significantly different. In conclusion, this study shows that systemic vasodilatation mainly depends on an hyperproduction of endogenous vasodilators acting on second messenger systems but not on endogenous calcium antagonists. Moreover, it suggests that calcium and K + ATP channels have a normal response to vasodilator substances.