Urotensinergic system genes in experimental subarachnoid hemorrhage / El sistema urotensinérgico en un modelo experimental de hemorragia subaracnoidea

Objective: Cerebral vasospasm, one of the main complications of subarachnoid hemorrhage (SAH), is characterized by arterial constriction and mainly occurs from day 4 until the second week after the event. Urotensin-II (U-II) has been described as the most potent vasoconstrictor peptide in mammals. An analysis is made of the serum U-II concentrations and mRNA expression levels of U-II, urotensin related peptide (URP) and urotensin receptor (UT) genes in an experimental murine model of SAH. Design: An experimental study was carried out. Setting: Experimental operating room of the Biomedicine Institute of Seville (IBiS), Virgen del Rocío University Hospital (Seville, Spain). Participants: 96 Wistar rats: 74 SAH and 22 sham intervention animals. Interventions: Day 1: blood sampling, followed by the percutaneous injection of 100μl saline (sham) or blood (SAH) into the subarachnoid space. Day 5: blood sampling, followed by sacrifice of the animals. Main variables of interest: Weight, early mortality, serum U-II levels, mRNA values for U-II, URP and UT. Results: Serum U-II levels increased in the SAH group from day 1 (0.62pg/mL [IQR 0.36-1.08]) today 5 (0.74pg/mL [IQR 0.39-1.43]) (p<0.05), though not in the sham group (0.56pg/mL [IQR 0.06-0.83] day 1; 0.37pg/mL [IQR 0.23-0.62] day 5; p=0.959). Between-group differences were found on day 5 (p<0.05). The ROC analysis showed that the day 5 serum U-II levels (AUC=0.691), URP mRNA (AUC=0.706) and UT mRNA (AUC=0.713) could discriminate between sham and SAH rats. The normal serum U-II concentration range in rats was 0.56pg/mL (IQR 0.06-0.83). Conclusion: The urotensinergic system is upregulated on day 5 in an experimental model of SAH (AU)

Objetivo: El vasoespasmo cerebral, una de las principales complicaciones secundarias a hemorragia subaracnoidea (HSA), se caracteriza por una constricción arterial que tiene lugar principalmente entre el día 4 y la segunda semana. La urotensina-II (U-II) ha sido definida como el péptido con mayor capacidad vasoconstrictora en mamíferos. Quisimos analizar los niveles séricos de U-II, así como los niveles de expresión de los genes de U-II, péptido relacionado con urotensina y receptor de urotensina, en un modelo murino experimental de HSA. Diseño: Estudio experimental. Ámbito: Quirófano experimental del Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío. Participantes: Noventa y seis ratas Wistar: 74 con inyección percutánea de sangre (HSA), 22 con inyección percutánea de 100μL de salino (Sham). Intervenciones: Día 1: extracción de muestras de sangre. Posteriormente, inyección percutánea de 100μL de salino (Sham) o de sangre (HSA) en el espacio subaracnoideo. Día 5: extracción de muestras de sangre y sacrificio del animal. Principales variables de interés: Peso, mortalidad precoz, niveles séricos de U-II, valores de ARNm de U-II, péptido relacionado con urotensina y receptor de urotensina. Resultados: Observamos un incremento en los niveles de U-II sérica en el grupo HSA desde el día 1 (0,62pg/mL [RI 0,36-1,08]) al día 5 (0,74pg/mL [RI 0,39-1,43]) (p<0,05); pero no observamos tal diferencia en el grupo Sham (0,56pg/mL [RI 0,06-0,83] día 1; 0,37pg/mL [RI 0,23-0,62] día 5) (p=0,959). Se encontraron diferencias en los niveles de U-II entre ambos grupos al quinto día (p<0,05). El análisis de curvas ROC demostró que la U-II sérica al quinto día (AUC=0,691), ARNm de péptido relacionado con urotensina (AUC=0,706) y ARNm de receptor de urotensina (AUC=0,713) podían discriminar entre ratas Sham y HSA. Además, definimos un rango de normalidad para los niveles de U-II séricos en ratas: 0,56pg/mL (RI 0,06-0,83). Conclusión: Este estudio demuestra por primera vez que el sistema urotensinérgico ve incrementada su expresión en el quinto día en un modelo de HSA (AU)

Effect of vasodilation by milrinone, a phosphodiesterase III inhibitor, on vasospastic arteries after a subarachnoid hemorrhage in vitro and in vivo: effectiveness of cisternal injection of milrinone.

OBJECTIVE: Cerebral vasospasm remains a major cause of morbidity and mortality. Milrinone, a bipyridine phosphodiesterase III inhibitor, is a potent member of the inodilator class of cardiac agents for vasospasm and is injected intra-arterially or intracisternally. There have been no studies investigating the duration of action (context-sensitive half-life) of milrinone for vasospasm or the most effective route of administration (intra-arterial versus intracisternal). We examined the effects of intracisternal and intra-arterial injection of milrinone on chronic cerebral vasospasm in dogs. METHODS: A double-hemorrhage canine model was used. In a preliminary isometric tension study of canine vasospastic basilar arteries, the vasodilatory effects of milrinone were examined 7 days after an initial injection of blood. Milrinone was injected intracisternally (0.1 mg, 0.47 mmol/L) or intra-arterially (0.3 mg/kg, 1.2 mmol/L), and angiograms were performed 30, 60, 120, 180, 240, 300, and 360 minutes later on day 7. RESULTS: Milrinone produced concentration-dependent vasodilation and was effective intracisternally, resulting in significant dilation until 180 minutes after injection and a tendency for dilation until 240 minutes. The effect of intra-arterial injection was not as significant compared with an intracisternal injection, resulting in significant dilation only at 180 minutes after intra-arterial injection. CONCLUSION: Intracisternal injection of milrinone was more effective than intra-arterial injection for chronic cerebral vasospasm in dogs because intracisternal injection produced a higher concentration in vasospastic arteries (0.034-0.068 mmol/L intracisternally versus 0.016 mmol/L intra-arterially).

In vitro and in vivo effects of probucol on hydrolysis of asymmetric dimethyl L-arginine and vasospasm in primates.

OBJECT: Increased cerebrospinal fluid (CSF) levels of asymmetric dimethyl L-arginine (ADMA), an endogenous inhibitor of endothelial nitric oxide synthase (eNOS), are associated with delayed vasospasm after subarachnoid hemorrhage (SAH); however, the source, cellular mechanisms, and pharmacological inhibition of ADMA production following SAH are unknown. METHODS: In an in vitro experiment involving human umbilical vein endothelial cells (HUVECs), the authors examined mechanisms potentially responsible for increased ADMA levels during vasospasm and investigated whether this increase can be inhibited pharmacologically. In a second study, an in vivo experiment, the authors used probucol, which effectively inhibited ADMA increase in HUVEC cultures in vitro, in a randomized double-blind placebo-controlled experiment in a primate model of delayed cerebral vasospasm after SAH. Oxidized low-density lipids (OxLDLs; positive control; p < 0.02) and bilirubin oxidation products (BOXes; p < 0.01), but not oxyhemoglobin (p = 0.74), increased ADMA levels in HUVECs. Probucol inhibited changes in ADMA levels evoked by either OxLDLs (p < 0.001) or BOXes (p < 0.01). Comparable changes were observed in cell lysates. In vivo probucol (100 mg/kg by mouth daily) did not alter serum ADMA levels on Days 7, 14, and 21 after SAH compared with levels before SAH, and these levels were not different from those observed in the placebo group (p = 0.3). Despite achieving therapeutic levels in plasma and measurable levels in CSF, probucol neither prevented increased CSF ADMA levels nor the development of vasospasm after SAH. Increased CSF ADMA and decreased nitrite levels in both groups were strongly associated with the degree of delayed vasospasm after SAH (correlation coefficient [CC] 0.5, 95% confidence interval [CI] 0.19-0.72, p < 0.002 and CC -0.43, 95% CI -0.7 to -0.05, p < 0.03, respectively). CONCLUSIONS: Bilirubin oxidation products, but not oxyhemoglobin, increased ADMA levels in the HUVEC. Despite its in vitro ability to lower ADMA levels, probucol failed to inhibit increased CSF ADMA and decreased nitrite levels, and it did not prevent delayed vasospasm in a primate SAH model.

Controlled release of a nitric oxide donor for the prevention of delayed cerebral vasospasm following experimental subarachnoid hemorrhage in nonhuman primates.

OBJECT: Results of prior studies in rats and rabbits show that the alteration of vasomotor tone in vasospasm following periadventitial blood exposure may be reversed, at least in part, by the administration of compounds releasing nitric oxide (NO). The authors have now generalized this finding to nonhuman primates. METHODS: Ten cynomolgus monkeys underwent cerebral angiography before and 7 days following the induction of subarachnoid hemorrhage (SAH) by the placement of 2 to 3 ml clotted autologous blood around the supraclinoid carotid, proximal anterior cerebral, and proximal middle cerebral arteries. An ethylene vinyl acetate copolymer, either blank (five animals) or containing 20% w/w (Z)-1-[2-(2-aminoethyl)-N-(2-aminoethyl)amino]diazen-1-ium-1,2-diolate (DETA/NO, 4.3 mg/kg; five animals) was placed adjacent to the vessels at the time of surgery. Animals were killed on Day 7 post-SAH following repeated cerebral angiography. The mean percentage of control vascular areal fraction was calculated from angiograms. Cerebral vessels were sectioned and the mean percentage of lumen patency was calculated. One animal that had received the DETA/NO polymer died prior to repeated angiography. In the remaining animals, DETA/NO caused a significant decrease in vasospasm compared with controls, according to both angiographic (84.8 +/- 8.6 compared with 56.6 +/- 5.2%, respectively, p < 0.05) and histological studies (internal carotid artery 99.3 +/- 1.8 compared with 60.1 +/- 4.4%, respectively, p < 0.001; middle cerebral artery 98.4 +/- 3 compared with 56.1 +/- 3.7%, respectively, p < 0.001; and anterior cerebral artery 89.2 +/- 8.5 compared with 55.8 +/- 6.3%, respectively, p < 0.05). CONCLUSIONS: The controlled release of DETA/NO is effective in preventing delayed cerebral vasospasm in an SAH model in nonhuman primates. The death of one animal in the treatment group indicates that the present dosage is at the threshold between therapeutic efficacy and toxicity.