- Email: [email protected]
Modulation of histamine releasibility by endogenous and exogenous nitric oxide donors
MODULATION OF HISTAMINE RELEASABIL1TY BY ENDOGENOUS AND EXOGENOUS NITRIC OXIDE DONORS 1p.F, M a n n a i o n i , I M . G . D i Bello, IS. R a s p a n t i , 1L. M u g n a i ~ IV. R o m a n o , 2T. B a n i S a c c h i a n d 1E. M a s i n i lDepartment of Pharmacology and 2Human Anatomy and H i s t o l o g y , F l o r e n c e U n i v e r s i t y , 5 0 1 3 4 F l o r e n c e , Italy:
INVOLVEMENT OF S Y M P A T H E T I C TONE AND NO PRODUCTION IN A R T E R I A L AND VENOUS TONE CONTROL IN PREGNANT COMPARED TO N O N P R E G N A N T RATS. F~.Le Marquer-Domagala, M. Finet, J-L Freslon* Innothera, Dpt of Pharmacology, 10 av. P.V. Couturier, 94111 Arcueil France; *Lab Pharmaco Fac Pharmacie, 146 rue Ldo Saignat, 33 076 Bordeaux Cedex, France. Various studies have shown that arterial pressure and vascular resistance are decreased in pregnant compared to non-pregnant rats. Variations of sympathetic tone and/or NO production could be involved in these alterations. Thus, the aim o f the present study was to assess the contribution of these two factors on arterial and venous tone in pregnancy, using pithing and treatment with L-NAME, a NO-synthase inhibitor. Mean arterial pressure (MAP) and mean circulatory filling pressure (MCFP, according t o Yamamoto et al., Am. J. Physiol., 1980, 238, H823-H828) were assessed in intact and pentobarbitone-anaesthetized 2 month-old virgin and pregnant (17 days of gestation) Wistar rats. Sanae measurements were made after pithing and pithing + L-NAME (bolus o f 30 mg/kg). Measurements were made when MAP and MCFP had reached stability, after pithing or pithing + L-NAME bolus. " In intact rats, MAP and MCFP were significantly lower in pregnant In=8) compared to virgin rats In=8): MAP (mm Hg): 115±6 vs 135±4, p<0.05; MCFP: 5.5±0.2 vs 6.6±0.3, p<0.01. After pithing, values were: MAP: 49±1 vs 49±3, NS; MCFP: 5.0±0.2 vs 4.6±0.2, NS, respectively for pregnant and virgin group, In intact rats, L-NAME-induced rises in MAP (expressed us % of initial MAP) were not significantly different in the pregnant compared to the virgin group: +29±1 vs +27±2, NS, but significantly lower when the same comparison was" made in pithed animals: +57_+5 vs +125±13, p<0.01. The same pattern of effect was observed for MCFP. These results suggest that in pregnant compared to non-pregnant rats 1)s~'mpathetic tone is weaker; 2) e n d o g e n o u s NO production is unchanged when estimated in intact animals but is weaker when estimated in pithed animals.
In hearts isolated from guinea pigs, ischaemia-reperfusion (IR) promoted a linear release of lactate dehydrogenase (LDH) and a preferential release of histamine in the reperfusion phase, The amount of nitrite (NO2-) released during IR was significantly lower than in sham operated hearts. These effects were accompanied by an increase in calcium levels and malonyldialdehyde (MDA) production in the left ventricle, by a decrease of cardiac mast cell (MC) metachromasia, and may be accounted for by the formation of reactive oxygen species. Defibrotide (DFT), a single strand oligonucleotide from bovine lungs, and relaxin (RLX), a peptide hormone secreted from the corpus luteum, have been shown to increase the coronary flow and the amount of NO2- in the perfusates, both in normally peffused guinea pig hearts, and in hearts submitted to IR. The effects were abated by inhibiting nitric oxide (NO) synthase. The perfusion of the heart with both DFT and RLX significantly reduced the release of histamine and LDH, the calcium overload and MDA production induced by IR, and the extent of degranulation of cardiac MC. Moreover, RLX increases the generation of NO2- from rat serosal MC, and both RLX and DFT diminish the releasability of histamine from rat and guinea pig MC stimulated with immunological and nonimmunological stimuli. In conclusion, DFT and RLX, as exogenous or endogenous NO donors, provide significant myocardial protection from IR and histamine release.
ROLE OF EXOGENOUS NITRATES ON CUTANEOUS MICROCIRCULATION OF HYPERTENSIVE PATIENTS, R. Nami. M. Mulinari, G. Guzzo. F. Pauza. A. Montagnam M Montagnani, C. Gennari. •Institute of lnlernal Medicine alid Medical Pathology. University of Siena. Italy.
I N D O M E T H A C I N (IND) I N C R E A S E S T H E N O F O R M A T I O N IN THE I S O L A T E D PERFUSED RAT KIDNEY (IPRK) AND IN H U M A N E N D O T H E L I A L CELLS (HEC) *H.Mota-Filipc.**H~Luz-Rodrigues,*B.Silva-Lima and**J.MGi~_o T.Rico *Lab.Pharmacology, Faculty of Pharmacy, **Institute of Pharmacology Faculty of ,Medicine , Av. For~as Armadas, Lisboa, Portugal.
It is well known that exogenous nitrates exert relaxation on the vascular wall via the release of nitric oxide (NO), which has been recently identified as endolhelium-derived rclaxing factor (EDRF). Moreover, it has been seen thal in the absence of producnon or release of endogenous EDFR. i.e. in arteriosclerotic vessels or m endothelium-free vessel segmems, exogenous nitrates remain fidly effective. Conversely. the effect of nitro-vasodilators Is reduced if an endogenous basal release of NO is present. Therefore. the a~m of the present study was to cvalnate the effect of isosorbide dinitrate 5 mg (ISDN). sublingually administered, on cutaneous microcirculation in 5 patients suffering from untreated and tmcomplicated essential arterial hypertension (EAH) (3M. 2F mean age:42.8±5.7 SE years) compared with 5 sex- and age-matched healthy norntotensive subjects IN). In the morning, before and after ISDN. serial measurements of sitting systolic and diastolic BP and heart rate (HR) toscillomelric method) were made and a peri-ungual capiUaroscopy, nsmg a video-microscopy system was performed, with m vivo and m real-time evalualion of dynamic and static nttrate-induced changes occurmg m cutaneous nucrocirculation Before ISDN. a rednclion in capillary density' was observed in EAH patienls. when compared to N subjects. After ISDN. m both the groups arteriolar dilation preceded venular dilanon. However. m EAH patlenls, arteriolar dilation was more precocious and marked than m N subjects. Moreover. m EAH patients, the perccntual decrease of systolic and diastolic BP and the percentual increase of HR observed after ISDN. were significanlly greater than those of N subjects. Results of our stud)" comqrm thai Ihe vasodilative action of exogcnous nurates is present in cutaneous microcirculation, and it is fldly effective m hypertensive panenls, in whom an endogenous release of NO appears to be reduced because of the cndothelial damage secondary 1o the hypenenswe process.
The endothe[ium plays a pivotal role on the modulation of the vascular tone by producing several mediators, namely the vasodi[ators nitric oxide (NO) and eyelooxygenase (COX)-derived arachidonic acid lnetabolites. In order to investigate the relationship between the COX and the NO pathways we have studied the effect of COX inhibition by IND 5.6p, M on the NO formation in IPRK stimulated with noradrenaline 0.6gM (NE). and in cultured HEC (obtained fi-om umbilical ~,eins) stimulated with earbachol [0~_tM (CCh). In [PRK the perfusion pressure was momtored and the venous effluents collected. The HEC were incubated in MEM with Cch: IND 5.6p, M+CCh: N(~-Nitro-L-arginine (L-NOARG) 10t,tM+CCh or L-NOARG+IN D+CCh. The NO levels were measured by the Griess reaction which assays NO~-, In the IPRK the NE increased the perfusion pressure and the NO levels in tlte venous effluents (nmol rain) from 9.4-LI.4 (basal) to 17.23:2.8": subsequently the perfusion pressure was and the NO levels also decreased to 10.6~1.1. The subsequent perfusion with IND increased the levels to 17.4±2.3". L-NOARG reduced this mcrease to 13.8±1.9"(*P<0.05). In IIEC the CCh increased the NO l'dvels (nmol/10°cells) fi'om 6.76±0.13 to 7.9~-0.1 *. With IND +CCh. 9.03:0.3* was obtained (*P<0.05~. The L-NOARG reduced the NO formation by CCh and by IND+CCh. simultaneously to 5.5:~(I,I and 6.1±0.2.The results suggest that COX inhibition induces an enhance of the NO probably due to an inhibition of superoxide production (Scrub and Vaage. 1991 ), Scrub. AG. and J Vaage. 1991. Scand J Clin Lab Invest:51.377-383
--
62
--
INVOLVEMENT OF S Y M P A T H E T I C TONE AND NO PRODUCTION IN A R T E R I A L AND VENOUS TONE CONTROL IN PREGNANT COMPARED TO N O N P R E G N A N T RATS. F~.Le Marquer-Domagala, M. Finet, J-L Freslon* Innothera, Dpt of Pharmacology, 10 av. P.V. Couturier, 94111 Arcueil France; *Lab Pharmaco Fac Pharmacie, 146 rue Ldo Saignat, 33 076 Bordeaux Cedex, France. Various studies have shown that arterial pressure and vascular resistance are decreased in pregnant compared to non-pregnant rats. Variations of sympathetic tone and/or NO production could be involved in these alterations. Thus, the aim o f the present study was to assess the contribution of these two factors on arterial and venous tone in pregnancy, using pithing and treatment with L-NAME, a NO-synthase inhibitor. Mean arterial pressure (MAP) and mean circulatory filling pressure (MCFP, according t o Yamamoto et al., Am. J. Physiol., 1980, 238, H823-H828) were assessed in intact and pentobarbitone-anaesthetized 2 month-old virgin and pregnant (17 days of gestation) Wistar rats. Sanae measurements were made after pithing and pithing + L-NAME (bolus o f 30 mg/kg). Measurements were made when MAP and MCFP had reached stability, after pithing or pithing + L-NAME bolus. " In intact rats, MAP and MCFP were significantly lower in pregnant In=8) compared to virgin rats In=8): MAP (mm Hg): 115±6 vs 135±4, p<0.05; MCFP: 5.5±0.2 vs 6.6±0.3, p<0.01. After pithing, values were: MAP: 49±1 vs 49±3, NS; MCFP: 5.0±0.2 vs 4.6±0.2, NS, respectively for pregnant and virgin group, In intact rats, L-NAME-induced rises in MAP (expressed us % of initial MAP) were not significantly different in the pregnant compared to the virgin group: +29±1 vs +27±2, NS, but significantly lower when the same comparison was" made in pithed animals: +57_+5 vs +125±13, p<0.01. The same pattern of effect was observed for MCFP. These results suggest that in pregnant compared to non-pregnant rats 1)s~'mpathetic tone is weaker; 2) e n d o g e n o u s NO production is unchanged when estimated in intact animals but is weaker when estimated in pithed animals.
In hearts isolated from guinea pigs, ischaemia-reperfusion (IR) promoted a linear release of lactate dehydrogenase (LDH) and a preferential release of histamine in the reperfusion phase, The amount of nitrite (NO2-) released during IR was significantly lower than in sham operated hearts. These effects were accompanied by an increase in calcium levels and malonyldialdehyde (MDA) production in the left ventricle, by a decrease of cardiac mast cell (MC) metachromasia, and may be accounted for by the formation of reactive oxygen species. Defibrotide (DFT), a single strand oligonucleotide from bovine lungs, and relaxin (RLX), a peptide hormone secreted from the corpus luteum, have been shown to increase the coronary flow and the amount of NO2- in the perfusates, both in normally peffused guinea pig hearts, and in hearts submitted to IR. The effects were abated by inhibiting nitric oxide (NO) synthase. The perfusion of the heart with both DFT and RLX significantly reduced the release of histamine and LDH, the calcium overload and MDA production induced by IR, and the extent of degranulation of cardiac MC. Moreover, RLX increases the generation of NO2- from rat serosal MC, and both RLX and DFT diminish the releasability of histamine from rat and guinea pig MC stimulated with immunological and nonimmunological stimuli. In conclusion, DFT and RLX, as exogenous or endogenous NO donors, provide significant myocardial protection from IR and histamine release.
ROLE OF EXOGENOUS NITRATES ON CUTANEOUS MICROCIRCULATION OF HYPERTENSIVE PATIENTS, R. Nami. M. Mulinari, G. Guzzo. F. Pauza. A. Montagnam M Montagnani, C. Gennari. •Institute of lnlernal Medicine alid Medical Pathology. University of Siena. Italy.
I N D O M E T H A C I N (IND) I N C R E A S E S T H E N O F O R M A T I O N IN THE I S O L A T E D PERFUSED RAT KIDNEY (IPRK) AND IN H U M A N E N D O T H E L I A L CELLS (HEC) *H.Mota-Filipc.**H~Luz-Rodrigues,*B.Silva-Lima and**J.MGi~_o T.Rico *Lab.Pharmacology, Faculty of Pharmacy, **Institute of Pharmacology Faculty of ,Medicine , Av. For~as Armadas, Lisboa, Portugal.
It is well known that exogenous nitrates exert relaxation on the vascular wall via the release of nitric oxide (NO), which has been recently identified as endolhelium-derived rclaxing factor (EDRF). Moreover, it has been seen thal in the absence of producnon or release of endogenous EDFR. i.e. in arteriosclerotic vessels or m endothelium-free vessel segmems, exogenous nitrates remain fidly effective. Conversely. the effect of nitro-vasodilators Is reduced if an endogenous basal release of NO is present. Therefore. the a~m of the present study was to cvalnate the effect of isosorbide dinitrate 5 mg (ISDN). sublingually administered, on cutaneous microcirculation in 5 patients suffering from untreated and tmcomplicated essential arterial hypertension (EAH) (3M. 2F mean age:42.8±5.7 SE years) compared with 5 sex- and age-matched healthy norntotensive subjects IN). In the morning, before and after ISDN. serial measurements of sitting systolic and diastolic BP and heart rate (HR) toscillomelric method) were made and a peri-ungual capiUaroscopy, nsmg a video-microscopy system was performed, with m vivo and m real-time evalualion of dynamic and static nttrate-induced changes occurmg m cutaneous nucrocirculation Before ISDN. a rednclion in capillary density' was observed in EAH patienls. when compared to N subjects. After ISDN. m both the groups arteriolar dilation preceded venular dilanon. However. m EAH patlenls, arteriolar dilation was more precocious and marked than m N subjects. Moreover. m EAH patients, the perccntual decrease of systolic and diastolic BP and the percentual increase of HR observed after ISDN. were significanlly greater than those of N subjects. Results of our stud)" comqrm thai Ihe vasodilative action of exogcnous nurates is present in cutaneous microcirculation, and it is fldly effective m hypertensive panenls, in whom an endogenous release of NO appears to be reduced because of the cndothelial damage secondary 1o the hypenenswe process.
The endothe[ium plays a pivotal role on the modulation of the vascular tone by producing several mediators, namely the vasodi[ators nitric oxide (NO) and eyelooxygenase (COX)-derived arachidonic acid lnetabolites. In order to investigate the relationship between the COX and the NO pathways we have studied the effect of COX inhibition by IND 5.6p, M on the NO formation in IPRK stimulated with noradrenaline 0.6gM (NE). and in cultured HEC (obtained fi-om umbilical ~,eins) stimulated with earbachol [0~_tM (CCh). In [PRK the perfusion pressure was momtored and the venous effluents collected. The HEC were incubated in MEM with Cch: IND 5.6p, M+CCh: N(~-Nitro-L-arginine (L-NOARG) 10t,tM+CCh or L-NOARG+IN D+CCh. The NO levels were measured by the Griess reaction which assays NO~-, In the IPRK the NE increased the perfusion pressure and the NO levels in tlte venous effluents (nmol rain) from 9.4-LI.4 (basal) to 17.23:2.8": subsequently the perfusion pressure was and the NO levels also decreased to 10.6~1.1. The subsequent perfusion with IND increased the levels to 17.4±2.3". L-NOARG reduced this mcrease to 13.8±1.9"(*P<0.05). In IIEC the CCh increased the NO l'dvels (nmol/10°cells) fi'om 6.76±0.13 to 7.9~-0.1 *. With IND +CCh. 9.03:0.3* was obtained (*P<0.05~. The L-NOARG reduced the NO formation by CCh and by IND+CCh. simultaneously to 5.5:~(I,I and 6.1±0.2.The results suggest that COX inhibition induces an enhance of the NO probably due to an inhibition of superoxide production (Scrub and Vaage. 1991 ), Scrub. AG. and J Vaage. 1991. Scand J Clin Lab Invest:51.377-383
--
62
--