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Nitric oxide modulates the muscular tone of the rabbit detrusor
EFFECT O F THE INHIBITION O F THE NITRIC OXIDE (NO)sYNTHASE ON THE RABBIT AND GUINEA-PIG ILEAL CONTRACTILITY, *B.Silva-Lima, *A.Ramos, *S.Vargas *H.Mota-Fil pe. ~*[I.Luz-Rodrigues and * ~.I.M .Gi~io T.Rico *Lab.Pharmacology, Faculty of Pharmacy,**lnstitute of Pharmacology Faculty of.Medicine Av.Forqas Armadas, 1600 Lisboa, Portugal
MODULATION BY NITRIC OXIDE OF THE SPONTANEOUS CONTRACTIONS OF ISOLATED GUINEA PIG TAENIA COLI
C.San~os, C.Caballero, P . P u i g - P a r e l l a d a Unitat de Farmacologia. "Facultat de Medicina. U n i v e r s i t a t de Barcelona. SPAIN. Nitric oxide (NO) is synthesised in the intestinal tract, plays a critical role in the co-ordinated propagation of gut contents and serves as a physiological legulator of electroly~e secretion. Furthermore NO is involved in gastrointestinal tract disorders. In the present study we investigated the roles of ~wo inhibitors of NO-synthase (L.NOARG 10 -~ M and L.NAME i0 -'~ M) and one NO donor (sodium nitroprusside, NPS, i0 -a M i0 -~ M) in spontaneous contractions of guinea pig isolated taenia coli in the presence of atropine I0 -° M and guanethidine 4.10 -~ M. We also assayed the nitrites released into the incubation m e d i u m b y Griess reagent. Our results show that both inhibitors of NO-synthase increase the frequency of c o n t r a c t i o n w h i c h is expressed b y a significant decrease in the time interval
The role of NO on tile modulation of the tone of nonvascular smooth muscle. like the gastrointestinal is starting to be mvesngated. In order to contribute to the c[arification of this issue, we have studied, in the ileal longitudinal smooth muscle of the guinea-pig {l,s.m,) the effect of the guanylcyclase tas an NO target enzyme/ inhibition by methylene blue (MB) on acetylcholine (AChJinduced responses. We have also studied in another intestinal preparanon, the rabbit ileum, the consequences on the ACh-dose-resnonse curve, of the inhibition of NO-synthase by NG-Nitro-L-argmine (NOARG'L ACh-dose-response curves were obtained In ,he I.s.m Afterwards the preparation was incubated with 2.5pM of MB and responses to 100nM of ACh were obtained. In rabbit ileum preparations. ACh-dose-response curves were also obtained, successivel3 ill the absence [comroH and in tile presence of I 0 u M of NOARG and I 0J_tM of NOARG I-100J_tM of [,-ARG. In the I.s.m. the MB decreased the 100 nM ACh-induced response to 85%_+9% of tile control which was 1420±250mg (n=6; P<0.05/. In the rabbit ileum, the NOARG decreased the ACh Emax to 82%±4% of the control which was 4172± 726mg (n-9: P<0.01lWith both NOARG+ L-ARG the Emax was not changed (3383+_682mg) as compared with NOARG alone. The ED50% in the control curvc was of 11 I nM±15 and did nol change n conseqnence of NOARG or NOARG+L-ARG. Thc rcsults suggest that tile NO similarly influences tile contractility of tile intestinal muscle in tile rabbit and in tile guinea-pig, by mcreasi'ng the magnitude of me responses reduced by acctylcholine, and agree with the observations of other Authors in the guinea-pig and in /he ral leum ~Barth6 and Lel'cb~ re. 1994: 1994a i.
b e t w e e n contractions (22.4 n=7, for L . N O A R G and 48.8
n=10, for L.NAME). In contrast the NO donor, NPS, showed a dose-dependent inhibition of the spontaneous contractions. The nitrites released into the incubation m e d i u m were reduced b y 58% in the presence of L.NAME. T h e s e d a t a p r o v i d e e v i d e n c e that NO is a n i m p o r t a n t m o d u l a t o r of the spontaneous contractions of gulnea pig t a e n i a coli.
Lorand Barth6. Romain Lefebvre. 994. EurJ,Phamtacol. 259. 101. Lorand Barth6_ Romain [,efebvre. 1994a. Naunyn-Schmiedcberg s Arch.Pbarmacol. 350, 582.
NITRIC OXIDE MODULATES PROSTAGLANDIN B I O S Y N T H E S I S IN T H E R A T .L=Sau_t_e_b_i~j. A. lalenti. A lanaro and M Di Rosa Department o f Experimental P h a r a t a e o l o g y , Uni~,ersity o f Naples "Federico II" _ Via Montesano 49_ 80131 Naples. ltah' M o d u l a h o n o f prostaglandhl (PG) bios~,nthesis in r i v e b} either exogenous or e n d o g e n o u s m m c oxide (NO) has been studied in the rat using arachidonic acid ( A A ) - i n d u c e d p a w o e d e m a and m c a s n r m g both the foot volume and thc a m o u n t o f 6 - k e t o - P G F in the o e d c m a t o u s fired recovered f r o m inflamed paws. P a w injection o f 150 or 300 nmol of A A were virtually inactive whereas 600 n m o l p r o d u c e d a moderate o e d e m a which was greatly reduced by the N O s3nthase inhibitor L-N~Lmtro arginme methyl ester ( L - N A M E . I(10 n m o l / p a w ) and the NO s c a v e n g e r h a e m o g l o b i n (Hb, 30 gruel/paw), but unaffected by the inhibitor o f the soluble g u a n y l a t c c3 clase methylen blue (Mb, 3 g m o l / p a w ) and L-argininc tl 5 gmol/paw~. The N O d o n o r 3-morpholino-s3 d n o n i m i a e hydrochloride (SIN-I ~ produced a dose-dependent (2.5, 5 . 1 0 gntobpax~ ) increase o f the oedema induced b-v A A (300 n m o l / p a ~ ) . In all the experiments the severity o f thc o c d c m a was corrclatcd with increased amounts o f 6-ketoP G F in the fluid recovered front the inflamed paw. Both o e d e m a and PG biosynthcsis induccd b3 the c o m b i n a t i o n o f A A (300 nmol/pawH-SIN-I (10gmol/pa~,~) were g r e a t b suppressed by eithcr Hb (30 lamol/paw) or indometltacin (3 ~tmol, p a w or 5 m g / K g s,c.) but unaffected by Mb (3 gmol/paw). In LPS-treated rats ( 6 m g / K g i.p,) doscs of A A inactive m normal animals p r o d u c e d a r e m a r k a b l e o c d e m a w h i c h was reduccd by L - N A M E (10(I n m o l / p a ~ ) or Hb (30 gruel/pax:v) unaffected by M b (3 g m o l / p a ~ ' ) and increased by L-argininc (15 gruel/paw), These results d e m o n s t r a t e that N O increases PG biosynthesis in r i v e through a c G M P - i n d c p e n d e n t m e c h a n i s m and suggest that the interaction bctwccn N O synthase and c y c l o o x y g c n a s e m a ) represent an important m e c h a n i s m for the m o d n l a t i o n o f the i n f l a m m a t o r y r e s p o n s e .
~: 8.2 ~, p< 0.03, ± 6.9 %, p=0.012,
NITRIC OXIDE MODULATES THE MUSCULAR TONE OF THE RABBIT DETRUSOR. *B.Si [va-Lima. *A.Ramos, *H.Mota-Filipe, **H.Luz-Rodrigucs and "*J.M.Gi~.o T. Rico *Lab.Pharmacology, Faculty of Pharmacy.**lnstitute o f Pharmacology Faculty of.Medicine Av.For~as Armadas. 1600 l,isboa. Portugal Nitric Oxide (NO) is a vasodilator which if formed in the endothelium, in consequence of different chemical or mechanical stimulus, ann modulates the vascular tone. A possible role tbr this mediator on the modulation o f the tone ofnenvascular smooth muscle like the m'inarv has been recentl} described. We have thus studied, in the rabbit detrusor, the effect of the inhibition of NO synthase with NG-Nitro-l,-arginine (NOARG) on the acetylcholinc doseresponse curves, and the cffect of the guanylcyclase inhibition with meth~ tene blue (MB). on l gM ACh and carbachol (CCh ~-induced responses. ACh dose-response curves were sucessively obtained m the absence tcontrol3 and in the presence of 10gM of NOARG or 101.tM NOARG+100p.M L-ARG. In other group of experiments after obtaining ACh or CCh dose-response curves, the preparations were incubated with 2.5tiM o f MB and responses to I ~tM o f l h e stimulants were obtained. The ACh Emax in tile control curve was 3485J:700 rag. The ED50 was 6.8-LI.2 tiM. The NOARG significantly increased the ACh Emax to I18%±8% of the control In-10:l'<0.05). Subsequently, in the simultaneous presence o f L-ARG and NOARG the m a g m t u d e o f the Emax has returned to the control values iEmax 106%±1 I%'k The ED50 was not changed b3 NOARG or NOARG+LARG. The MB also increased the response to II.tM of ACh from 568m112mg to 1224~204mg (n:6; P<0.05), and to Ig M of CCh from 640±60mg to 1560÷~00n~g.(n=6:P<0.05 I. The results suggest that, in the rabbit detrusor, the guanylcyclase system, wlaich is a component of the NO effector system is present and may have an intervention in the ACh and CCh-induced responses, find that the NO modulates the increase of the muscular tone induced by ACh. as the responses to the agonist were increased by NO synthasc inhibition.
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MODULATION BY NITRIC OXIDE OF THE SPONTANEOUS CONTRACTIONS OF ISOLATED GUINEA PIG TAENIA COLI
C.San~os, C.Caballero, P . P u i g - P a r e l l a d a Unitat de Farmacologia. "Facultat de Medicina. U n i v e r s i t a t de Barcelona. SPAIN. Nitric oxide (NO) is synthesised in the intestinal tract, plays a critical role in the co-ordinated propagation of gut contents and serves as a physiological legulator of electroly~e secretion. Furthermore NO is involved in gastrointestinal tract disorders. In the present study we investigated the roles of ~wo inhibitors of NO-synthase (L.NOARG 10 -~ M and L.NAME i0 -'~ M) and one NO donor (sodium nitroprusside, NPS, i0 -a M i0 -~ M) in spontaneous contractions of guinea pig isolated taenia coli in the presence of atropine I0 -° M and guanethidine 4.10 -~ M. We also assayed the nitrites released into the incubation m e d i u m b y Griess reagent. Our results show that both inhibitors of NO-synthase increase the frequency of c o n t r a c t i o n w h i c h is expressed b y a significant decrease in the time interval
The role of NO on tile modulation of the tone of nonvascular smooth muscle. like the gastrointestinal is starting to be mvesngated. In order to contribute to the c[arification of this issue, we have studied, in the ileal longitudinal smooth muscle of the guinea-pig {l,s.m,) the effect of the guanylcyclase tas an NO target enzyme/ inhibition by methylene blue (MB) on acetylcholine (AChJinduced responses. We have also studied in another intestinal preparanon, the rabbit ileum, the consequences on the ACh-dose-resnonse curve, of the inhibition of NO-synthase by NG-Nitro-L-argmine (NOARG'L ACh-dose-response curves were obtained In ,he I.s.m Afterwards the preparation was incubated with 2.5pM of MB and responses to 100nM of ACh were obtained. In rabbit ileum preparations. ACh-dose-response curves were also obtained, successivel3 ill the absence [comroH and in tile presence of I 0 u M of NOARG and I 0J_tM of NOARG I-100J_tM of [,-ARG. In the I.s.m. the MB decreased the 100 nM ACh-induced response to 85%_+9% of tile control which was 1420±250mg (n=6; P<0.05/. In the rabbit ileum, the NOARG decreased the ACh Emax to 82%±4% of the control which was 4172± 726mg (n-9: P<0.01lWith both NOARG+ L-ARG the Emax was not changed (3383+_682mg) as compared with NOARG alone. The ED50% in the control curvc was of 11 I nM±15 and did nol change n conseqnence of NOARG or NOARG+L-ARG. Thc rcsults suggest that tile NO similarly influences tile contractility of tile intestinal muscle in tile rabbit and in tile guinea-pig, by mcreasi'ng the magnitude of me responses reduced by acctylcholine, and agree with the observations of other Authors in the guinea-pig and in /he ral leum ~Barth6 and Lel'cb~ re. 1994: 1994a i.
b e t w e e n contractions (22.4 n=7, for L . N O A R G and 48.8
n=10, for L.NAME). In contrast the NO donor, NPS, showed a dose-dependent inhibition of the spontaneous contractions. The nitrites released into the incubation m e d i u m were reduced b y 58% in the presence of L.NAME. T h e s e d a t a p r o v i d e e v i d e n c e that NO is a n i m p o r t a n t m o d u l a t o r of the spontaneous contractions of gulnea pig t a e n i a coli.
Lorand Barth6. Romain Lefebvre. 994. EurJ,Phamtacol. 259. 101. Lorand Barth6_ Romain [,efebvre. 1994a. Naunyn-Schmiedcberg s Arch.Pbarmacol. 350, 582.
NITRIC OXIDE MODULATES PROSTAGLANDIN B I O S Y N T H E S I S IN T H E R A T .L=Sau_t_e_b_i~j. A. lalenti. A lanaro and M Di Rosa Department o f Experimental P h a r a t a e o l o g y , Uni~,ersity o f Naples "Federico II" _ Via Montesano 49_ 80131 Naples. ltah' M o d u l a h o n o f prostaglandhl (PG) bios~,nthesis in r i v e b} either exogenous or e n d o g e n o u s m m c oxide (NO) has been studied in the rat using arachidonic acid ( A A ) - i n d u c e d p a w o e d e m a and m c a s n r m g both the foot volume and thc a m o u n t o f 6 - k e t o - P G F in the o e d c m a t o u s fired recovered f r o m inflamed paws. P a w injection o f 150 or 300 nmol of A A were virtually inactive whereas 600 n m o l p r o d u c e d a moderate o e d e m a which was greatly reduced by the N O s3nthase inhibitor L-N~Lmtro arginme methyl ester ( L - N A M E . I(10 n m o l / p a w ) and the NO s c a v e n g e r h a e m o g l o b i n (Hb, 30 gruel/paw), but unaffected by the inhibitor o f the soluble g u a n y l a t c c3 clase methylen blue (Mb, 3 g m o l / p a w ) and L-argininc tl 5 gmol/paw~. The N O d o n o r 3-morpholino-s3 d n o n i m i a e hydrochloride (SIN-I ~ produced a dose-dependent (2.5, 5 . 1 0 gntobpax~ ) increase o f the oedema induced b-v A A (300 n m o l / p a ~ ) . In all the experiments the severity o f thc o c d c m a was corrclatcd with increased amounts o f 6-ketoP G F in the fluid recovered front the inflamed paw. Both o e d e m a and PG biosynthcsis induccd b3 the c o m b i n a t i o n o f A A (300 nmol/pawH-SIN-I (10gmol/pa~,~) were g r e a t b suppressed by eithcr Hb (30 lamol/paw) or indometltacin (3 ~tmol, p a w or 5 m g / K g s,c.) but unaffected by Mb (3 gmol/paw). In LPS-treated rats ( 6 m g / K g i.p,) doscs of A A inactive m normal animals p r o d u c e d a r e m a r k a b l e o c d e m a w h i c h was reduccd by L - N A M E (10(I n m o l / p a ~ ) or Hb (30 gruel/pax:v) unaffected by M b (3 g m o l / p a ~ ' ) and increased by L-argininc (15 gruel/paw), These results d e m o n s t r a t e that N O increases PG biosynthesis in r i v e through a c G M P - i n d c p e n d e n t m e c h a n i s m and suggest that the interaction bctwccn N O synthase and c y c l o o x y g c n a s e m a ) represent an important m e c h a n i s m for the m o d n l a t i o n o f the i n f l a m m a t o r y r e s p o n s e .
~: 8.2 ~, p< 0.03, ± 6.9 %, p=0.012,
NITRIC OXIDE MODULATES THE MUSCULAR TONE OF THE RABBIT DETRUSOR. *B.Si [va-Lima. *A.Ramos, *H.Mota-Filipe, **H.Luz-Rodrigucs and "*J.M.Gi~.o T. Rico *Lab.Pharmacology, Faculty of Pharmacy.**lnstitute o f Pharmacology Faculty of.Medicine Av.For~as Armadas. 1600 l,isboa. Portugal Nitric Oxide (NO) is a vasodilator which if formed in the endothelium, in consequence of different chemical or mechanical stimulus, ann modulates the vascular tone. A possible role tbr this mediator on the modulation o f the tone ofnenvascular smooth muscle like the m'inarv has been recentl} described. We have thus studied, in the rabbit detrusor, the effect of the inhibition of NO synthase with NG-Nitro-l,-arginine (NOARG) on the acetylcholinc doseresponse curves, and the cffect of the guanylcyclase inhibition with meth~ tene blue (MB). on l gM ACh and carbachol (CCh ~-induced responses. ACh dose-response curves were sucessively obtained m the absence tcontrol3 and in the presence of 10gM of NOARG or 101.tM NOARG+100p.M L-ARG. In other group of experiments after obtaining ACh or CCh dose-response curves, the preparations were incubated with 2.5tiM o f MB and responses to I ~tM o f l h e stimulants were obtained. The ACh Emax in tile control curve was 3485J:700 rag. The ED50 was 6.8-LI.2 tiM. The NOARG significantly increased the ACh Emax to I18%±8% of the control In-10:l'<0.05). Subsequently, in the simultaneous presence o f L-ARG and NOARG the m a g m t u d e o f the Emax has returned to the control values iEmax 106%±1 I%'k The ED50 was not changed b3 NOARG or NOARG+LARG. The MB also increased the response to II.tM of ACh from 568m112mg to 1224~204mg (n:6; P<0.05), and to Ig M of CCh from 640±60mg to 1560÷~00n~g.(n=6:P<0.05 I. The results suggest that, in the rabbit detrusor, the guanylcyclase system, wlaich is a component of the NO effector system is present and may have an intervention in the ACh and CCh-induced responses, find that the NO modulates the increase of the muscular tone induced by ACh. as the responses to the agonist were increased by NO synthasc inhibition.
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