Kalikreína vascular y cardíaca en hipertensión asociada a alteraciones del metabolismo lipídico / Cardiovascular kallikrein in hypertension associated to lipidic metabolic disorders

ANTECEDENTES: La hipertensión arterial y la hiperlipemia dañan el endotelio vascular y predisponen al desarrollo de lesiones ateromatosas y enfermedades coronarias. Las células endoteliales y musculares son capaces de modular la función cardiovascular mediante la producción de factores autocrino/paracrinos. Se ha descripto la presencia de un sistema generador de kininas en vasos y corazón. El propósito de este estudio es examinar si existe modificación de la actividad kininogenásica en tejido cardiovascular de ratas dislipidémicas e hipertensas por inhibición de la producción del factor relajante derivado del endotelio. MATERIAL Y METODO: Se utilizaron ratas Wistar macho (430 ñ 50 g peso), las que se sometieron a los siguientes tratamientos: control (n= 10): dieta normal; lípidos (n= 10): dieta con sobrecarga de 16 por ciento de ácidos grasos saturados y 2 por ciento de colesterol durante 8 semanas; L-NAME (n= 10): administración oral de un inhibidor de la síntesis de factor relajante endotelial, L-nitro arginina metil éster, 100 mg/kg/ día durante las 2 últimas semanas del período experimental; lípidos + L-NAME (n= 10): administración de dieta con sobrecarga grasa durante 8 semanas y de L-NAME durante las 2 últimas semanas. Se midió la presión arterial, la concentración de lípidos plasmáticos y la actividad kininogenásica en homogenados de corazón y vasos sanguíneos (pgBK/mg/h). Resultados: La manipulación dietética de los animales no produjo cambios en su presión arterial, pero fue efectiva para instaurar un perfil lipoproteico aterogénico (p< 0,05). La administración de L-NAME produjo un aumento significativo de los niveles tensionales (p< 0,05), sin modificar las concentraciones de los metabolitos plasmáticos dosados. La actividad kininogenásica presente en homogenados de corazón aumentó significativamente en los animales sometidos a sobrecarga dietética de grasa y ese incremento fue aún mayor cuando se les adicionó al agua de bebida el inhibidor de la síntesis de factor relajante endotelial (p< 0,05). Un patrón semejante se observa en homogenados de aorta, arterias caudales y venas caudales (p< 0,05). CONCLUSIONES: El incrmento local de la capacidad generadora de kininas en tejido cardiovascular podría representar un esfuerzo tisular por contraponerse a la agresión endotelial causada por el aumento de los lípidos plasmáticos y el aumento de la presión arterial. Las kininas liberadas in situ tendrían efectos hemodinámicos y metabólicos ...

Kalikreína vascular y cardíaca en hipertensión asociada a alteraciones del metabolismo lipídico / Cardiovascular kallikrein in hypertension associated to lipidic metabolic disorders

ANTECEDENTES: La hipertensión arterial y la hiperlipemia dañan el endotelio vascular y predisponen al desarrollo de lesiones ateromatosas y enfermedades coronarias. Las células endoteliales y musculares son capaces de modular la función cardiovascular mediante la producción de factores autocrino/paracrinos. Se ha descripto la presencia de un sistema generador de kininas en vasos y corazón. El propósito de este estudio es examinar si existe modificación de la actividad kininogenásica en tejido cardiovascular de ratas dislipidémicas e hipertensas por inhibición de la producción del factor relajante derivado del endotelio. MATERIAL Y METODO: Se utilizaron ratas Wistar macho (430 ñ 50 g peso), las que se sometieron a los siguientes tratamientos: control (n= 10): dieta normal; lípidos (n= 10): dieta con sobrecarga de 16 por ciento de ácidos grasos saturados y 2 por ciento de colesterol durante 8 semanas; L-NAME (n= 10): administración oral de un inhibidor de la síntesis de factor relajante endotelial, L-nitro arginina metil éster, 100 mg/kg/ día durante las 2 últimas semanas del período experimental; lípidos + L-NAME (n= 10): administración de dieta con sobrecarga grasa durante 8 semanas y de L-NAME durante las 2 últimas semanas. Se midió la presión arterial, la concentración de lípidos plasmáticos y la actividad kininogenásica en homogenados de corazón y vasos sanguíneos (pgBK/mg/h). Resultados: La manipulación dietética de los animales no produjo cambios en su presión arterial, pero fue efectiva para instaurar un perfil lipoproteico aterogénico (p< 0,05). La administración de L-NAME produjo un aumento significativo de los niveles tensionales (p< 0,05), sin modificar las concentraciones de los metabolitos plasmáticos dosados. La actividad kininogenásica presente en homogenados de corazón aumentó significativamente en los animales sometidos a sobrecarga dietética de grasa y ese incremento fue aún mayor cuando se les adicionó al agua de bebida el inhibidor de la síntesis de factor relajante endotelial (p< 0,05). Un patrón semejante se observa en homogenados de aorta, arterias caudales y venas caudales (p< 0,05). CONCLUSIONES: El incrmento local de la capacidad generadora de kininas en tejido cardiovascular podría representar un esfuerzo tisular por contraponerse a la agresión endotelial causada por el aumento de los lípidos plasmáticos y el aumento de la presión arterial. Las kininas liberadas in situ tendrían efectos hemodinámicos y metabólicos ... (AU)

Vascular kallikrein in deoxycorticosterone acetate-salt hypertensive rats.

We determined the status of vascular kallikrein in rats with severe hypertension caused by treatment with deoxycorticosterone acetate (DOCA) and drinking of 1% NaCl for 6 weeks. We assayed active and total kininogenase (kallikrein) activity in the perfusate and in arterial and venous tissue. DOCA-salt rats had higher systolic blood pressure at 6 weeks (214 +/- 5 mm Hg) than rats drinking tap water (135 +/- 4 mm Hg) or saline (145 +/- 8 mm Hg). Kininogenase in the perfusate (nanograms bradykinin per minute per kilogram body weight) increased significantly at 2 weeks, from 5.8 +/- 2.1 to 8.9 +/- 1.4 for active kallikrein and from 28.7 +/- 0.4 to 48.7 +/- 2.9 for total kallikrein. Total kallikrein returned to control values at 4 weeks, whereas it was significantly reduced at 6 weeks (20.9 +/- 0.7). Active kallikrein was significantly depressed at 4 and 6 weeks (1.08 +/- 0.1 and 0.85 +/- 0.1, respectively [P < .05]). Active kallikrein in arterial tissue (picograms bradykinin per milligram per minute) showed a small but significant increase at 2 weeks, from 156 +/- 7 to 201 +/- 10 (P < .05), finally decreasing significantly by 6 weeks to 64 +/- 3; however, total kallikrein showed a significant decrease only at 6 weeks, from 844 +/- 17 to 427 +/- 27. Both active and total kallikrein in the veins were higher than control values at 2 weeks, changing from 437 +/- 7 to 541 +/- 19 and from 1619 +/- 17 to 2062 +/- 86, respectively. Venous kallikrein remained elevated until the end of the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)

Kallikrein-like activity in nonpregnant and pregnant rat uterus, fetal membranes, placenta and amniotic fluid.

SBTI-resistant kininogenase activity was found in nonpregnant and pregnant rat uterus, placenta, amniotic fluid and fetal membranes. After trypsin treatment the kininogenase activity increased 2-3 fold. Total kininogenase (active plus inactive) was completely blocked by kallikrein antibodies. The physiological role of these kallikrein-like enzymes is unknown. It is speculated that these enzymes play a local role, perhaps in the processing of polypeptide hormones of through the release of kinins in the regulation of uterine blood flow.

The kallikrein--kinin system in blood vessels.

We have previously reported that vascular tissue contains kallikrein and kallikrein mRNA. We can now show that kallikrein is present throughout the vascular tree and is released from arterial and venous rings incubated "in vitro". Using the isolated perfused rat hindquarters as a model, we found that kallikrein appeared in the perfusate in concentrations that increased linearly with time. Treatment with puromycin inhibited kallikrein release by 87% (p < 0.01), these data suggest that kallikrein is synthesized and released by the vascular wall. Local generation of kinins (autocrine/paracrine system) may contribute to the regulation of vascular homeostasis.

Bradykinin-induced vasoconstriction of rat mesenteric arteries precontracted with noradrenaline.

1. Administration of bradykinin caused dose-dependent vasoconstriction in rat isolated perfused mesenteric arteries precontracted with noradrenaline. 2. The vasoconstrictor response was not mediated by BK1-bradykinin receptors. 3. Inhibition of cyclo-oxygenase with indomethacin, aspirin or meclofenamate abolished the vasoconstrictor effect of bradykinin, showing that a member of the arachidonic acid cascade may be involved. 4. Inhibitors of thromboxane synthesis (imidazole and UK 38485) did not affect or only reduced the bradykinin-induced vasoconstriction. 5. The endoperoxide H2/thromboxane A2 receptor antagonist SQ 29548 significantly reduced the vasoconstrictor effect of bradykinin, but did not affect the vasoconstrictor response to noradrenaline, adrenaline, vasopressin, 5-hydroxytryptamine or prostaglandins. 6. The eicosanoid(s) that mediate bradykinin-induced vasoconstriction appear to be synthesized outside the arterial endothelium. 7. The data suggest that the vasoconstrictor effect of bradykinin in the rat isolated mesenteric artery is mediated by vasoconstrictor arachidonic acid metabolites including the cyclic endoperoxides and/or the thromboxanes.

Kininogenase from rat vascular tissue.

A kininogenase resembling glandular kallikrein was partially purified from vascular tissue and characterized. Saline perfused rat tail arteries and veins were homogenized in 0.25 M sucrose containing 10 mM Tris-HCl (pH 7.4). The homogenate was centrifuged at 105,000 X g for 60 min and a vascular kininogenase was purified from the supernatant by chromatofocusing, affinity chromatography on immobilized antibodies against rat urinary kallikrein, and gel filtration on Sephadex G-100. The inhibitory effects of antibodies against rat urinary kallikrein were tested using equivalent kinin-forming concentrations of rat urinary kallikrein and vascular kininogenase. Kininogenase activities of both enzymes were similarly inhibited by urinary kallikrein antibodies. Aprotinin (1,000 KIU) completely inhibited vascular kininogenase activity while soybean trypsin inhibitor (100 micrograms) did not modify its kinin-forming activity. Vascular kininogenase and rat urinary kallikrein had the same elution volume when chromatographed on a Sephadex G-100 column and had similar mobilities in 10% polyacrylamide gel electrophoresis. Kinins released by vascular kininogenase were identified as bradykinin by reverse-phase high performance liquid chromatography. Rat vascular kininogenase appears to be similar to glandular kallikrein. Kinins released locally by vascular kininogenase may contribute to the regulation of vascular tone.

Kinin-forming enzymes in vascular tissue.

The present study was undertaken to examine whether there is a kallikrein-like enzyme in vascular tissue. Isolated saline-perfused rat mesenteric arteries were used. A kallikrein-like enzyme and acid protease from saline-perfused mesenteric arteries were separated by CM-cellulose chromatography with a linear NaCl gradient. The separation made it possible to study the optimum pH of the kallikrein-like enzyme and acid protease. The kallikrein-like enzyme showed optimal activity in the range of pH 7-9 and the acid protease in the range of pH 4-5. Both enzymes when acting on a protein plasma substrate release an active peptide that has a similar chemical and pharmacological properties to bradykinin. Using antibodies that specifically inhibit kinins, the biological action was completely abolished. These results indicate that arterial tissue contains two enzymes which generate kinins, the characteristics of one of the enzymes are quite similar to those of a lysosomal protease of the cathepsin-like type of enzyme and the other differs clearly from the acid protease and plasma kallikreins and has physicochemical characteristics quite similar to those of the kallikreins of glandular origin.

Active and inactive kallikrein released by kidney slices from normotensive and hypertensive rats.

The relative rates of release of active and inactive kallikrein were investigated in the rat kidney by studying in vitro kidney slices. The slices were kept in Warburg flasks in a Krebs-Ringer solution for 15 up to 60 minutes, and their kallikrein content and the kallikrein-like activity released by them were measured at different times. Renal kallikrein concentration from two-kidney, one clip hypertensive rats was less than in the sham-operated controls (p less than 0.01). Active kallikrein released into the bathing medium was 4.7 +/- 0.3 ng/mg/hr in normotensive rats (n = 10) and 3.3 +/- 0.3 in two-kidney hypertensive animals (n = 12); the difference between both groups was statistically significant (p less than 0.01). Inactive kallikrein is between 60% and 70% of the total kallikrein released by kidneys of normal and hypertensive rats. Thus, under the conditions of these experiments, the kidney slices were able to release a kallikrein-like enzyme in an active and an inactive form. The rate of active kallikrein released from slices of hypertensive animals was lower than in the normotensive controls.