Molecular analysis of genetic variation in angiotensin I-converting enzyme identifies no association with sporting ability: First report from Indian population.

INTRODUCTION: A polymorphism in the angiotensin-converting enzyme (ACE) gene was the first performance enhancing polymorphisms (PEPs) to be identified and correlated with athletic abilities. This polymorphism (rs. 5186) is the absence (deletion; D allele), rather than the presence (insertion, I allele) of 287bp Alu repeat element in intron 16. However, the association of ACE I/D polymorphism in sports abilities have been contradicted and debated. No study has evaluated the ACE gene polymorphism in Indian athletes so far. Hence, the genotype distribution and allelic frequency of ACE gene in selected Indian athletic and non-athletic population was studied. MATERIALS AND METHODS: A total of 147 athletes and 131 controls were genotyped for the ACE gene polymorphism using PCR. RESULTS: No significant association was observed between the allelic frequencies of ACE gene in controls and athletes on a whole, as well as after sub-categorizing the athletes based on the type of sport they played (P > 0.1). However, a higher representation of I allele was observed in the athletes. CONCLUSION: ACE genotyping studies need to focus on truly elite athletes of a single sporting discipline, to be able to find an association. The ACE I/D polymorphism may not be considered a marker for human performance, but can be further studied in combination with other potent performance enhancing polymorphisms.

La vía transduccional Rho A y Rho kinasa está activada en la pared arterial de ratas con niveles genéticamente elevados de angiotensina II / Transductional Rho A and Rho kynase pathways are activated in the arterial wall of rats with genetically elevated levels of angiotensin II

Antecedentes: El polimorfismo de la enzima convertidora de angiotensina I (ECA) determina mayor actividad de ECA yniveles de angiotensina (Ang) II en ratas Brown Norway (BN) y menor actividad de ECA y niveles de Ang II en ratas Lewis (L). La relación entre niveles de Ang II y la vía transduccional Rho A/Rho kinasa no ha sido explorada.Objetivo: Determinar la participación de la vía Rho A/ Rho kinasa mediante la fosforilación de la proteína blanco 1 de la fosfatasa de la miosina (MYPT1) vascular en ratas con niveles genéticamente bajos (L) y altos de Ang II (BN) y su relación con la expresión de algunos genes que determinan remodelado de la pared arterial: el gen del activador de plasminógeno 1 (PAI-1), el gen de la proteína quimioatractante de monocitos (MCP-1) y el gen del factor de transformación beta 1 (TGF- b1) en la pared arterial. Métodos: Se usaron ratas machos homocigotos de 150 grs BN y L. Para inhibir la vía Rho A / Rho kinasa, se administró fasudil (100 mg/Kg/día por gavage) a ratas BN, durante 7 días. Se determinó la presión arterial sistólica (PAS), la expresión vascular (en la aorta) de MYPT1 total (MYPT1-T) y MYPT1 fosforilada (MYPT1-P) y la relación entre ambas por Western blot además de la expresión génica de PAI-1, MCP-1 y de TGF-b1 por RT-PCR (en unidades de densidad óptica). Resultados como promedio(ES): El antagonista del receptor tipo I de angiotensina II Candesartán por 7 días (10 mg/Kg/d, n = 8) redujo en un 50 por ciento los niveles elevados de MYPT1-P/T en las ratas BN (p <0.05) sin modificar la mayor expresión de los genes evaluados. Conclusión: La vía Rho A/ Rho kinasa se encuentra activada en la pared arterial de ratas con niveles elevados de Ang II (BN) y causa mayor expresión génica de PAI-1 y de MCP-1 ya que la sobre expresión de ambos tiende a normalizarse con fasudil. La mayor expresión génica de TGF-b1 en la aorta en ratas BN parece no estar relacionada con la activación de de Rho A/ Rho kinasa vía Angiotensina II ya que no...

Efectos hipotalámicos de la angiotensina -[1-7] en ratas con coartación aórtica / Hypothalamic effects of angiotensin -[1-7] in rats with aortic coarctation

El objetivo del presente trabajo fue evaluar el efecto de la administración intrahipotalámica de la angiotensina -[1-7](Ang-[1-7]) sobre la presión arterial y la frecuencia cardíaca y sobre la actividad presora de la angiotensina II (Ang-II) en ratas con operación simulada (OS) o con coartación aórtica (CoAo) en un estadio temprano y en uno crónico de la hipertensión. Se utilizaron ratas Wistar. A los 7 y 42 días de la operación correspondiente se canuló una arteria carótida para la medición de la presión arterial media (PAM) en ratas anestesiadas y se insertó una aguja inyectora en el hipotálamo anterior para la administración de Ang-II (50 ng), Ang-[1-7] (50ng) y Ang-II + Ang-[1-7] (50 + 50 ng). La administración hipotálamica de Ang-II produjo un aumento de la PAM en las ratas CoAo con respecto al grupo control en los estadios temprano y crónico de hipertensión, mientras que la Ang-[1-7] redujo la actividad presora de la Ang-II en las ratas CoAo, mientras que careció de efecto sobre la actividad presora de la Ang-II en las ratas normotensas. En conclusión, la actividad presora de la Ang-II está aumentada en ratas en los estadios temprano y crónico de hipertensión arterial, mientras que el efecto antagónico de la Ang-[1-7] indicaría que ésta modularía la actividad presora de la angiotensina II cuando la Ang-II estuviera exacerbada, ya que se ha observado únicamente en el grupo de ratas hipertensas.

Role of endothelium in angiotensin II formation by the rat aorta and mesenteric arterial bed

We investigated the angiotensin II (Ang II)-generating system by analyzing the vasoconstrictor effect of Ang II, angiotensin I (Ang I), and tetradecapeptide (TDP) renin substrate in the abscence and presence of inhibitors of the renin-angiotensin system in isolated rat aortic rings and mesenteric arterial beds with and without functional endothelium. Ang II, Ang I, and TDP elicited a dose-dependent vasoconstrictor effect in both vascular preparations that was completely blocked by the Ang II receptor antagonist saralasin (50 nM). The angiotensin converting enzyme (ACE) inhibitor captopril (36 muM) completely inhibited the vasoconstrictor effect elicited by Ang I and TDP in aortic rings without affecting that of Ang II. In contrast, captopril (36 muM) significantly reduced (80-90 percent) the response to bolus injection of Ang I, without affecting those to Ang II and TDP in mesenteric arteries. Mechanical removal of the endothelium greatly potentiated (70-95 percent) the vasoconstrictor response to Ang II, Ang I, and TDP in aortic rings while these responses were unaffected by the removal of the endothelium of mesenteric arteries with sodium deoxycholate infusion. In addition, endothelium disruption did not change the pattern of response elicited by these peptides in the presence of captopril. These findings indicate that the endothelium may not be essential for Ang II formation in rat mesenteric arteries and aorta, but it may modulate the response to Ang II. Although Ang II formation from Ang I is essentially dependent on ACE in both vessels, our results suggest the existence of an alternative pathway in the mesenteric arterial bed that may play an important role in Ang II generation from TDP in resistence but not in large vessels during ACE inhibition.

Angiotensin converting activity assessed in vivo is increased in hereditary hypertensive rats

1. The angiotensin converting enzyme (ACE) activity of spontaneously hypertensive (SHR) and spontaneously hypertensive stroke-prone (SHRSP) rats was compared to the ACE activity of normotensive Wistar-Kyoto rats (WKY). 2. ACE activity was assessed indirectly in conscious unrestrained rats using the equipressor response end point to simultaneously calculate the extent of conversion of angiotensin I (AI) to angiotensin II (AII) and the pulmonary degradation of bradykinin (BK). 3. The pulmonary degradation of BK was significantly elevated (99.4%) in SHR rats whereas the elevation was not significant in SHRSP rats (99.2%) compared to WKY rats, even though the pulmonary inactivation of BK in WKY rats was higher (98.6%) than in normotensive Wistar rats (95.6% and 97.5%) previously studied. 4. Blood pressure responsiveness to intra-aortically injected BK (bolus injection and infusion) was markedly increased in SHR and SHRSP rats with no change in reactivity to sodium nitroprusside. 5. Conversion of AI to AII assessed by the equipressor doses of the hormones which produced a 20-mmHg rise in blood pressure was markedly elevated in SHR (86 +/- 4%) and SHRSP (80 +/- 7%) rats when compared to WKY rats (38 +/- 4%). 6. The marked increase in conversion of AI to AII in hypertensive animals, accompanied by an increased pulmonary degradation of BK in SHR rats, suggests that ACE activity is increased in conscious SHR and SHRSP rats and may participate in the genesis of hypertension in this model of genetic hypertension

Increased brainstem angiotensin-I levels in chronic 2 KIC hypertensive rats.

A study was undertaken on the role of brainstem renin-angiotensin system in maintenance of hypertension in chronic renovascular hypertensive rats. Hypertension was induced by unilateral renal artery clamping, while the contralateral kidney was left intact (2 KIC). Blood pressure (BP), plasma renin activity (PRA) and brainstem angiotensin (ang-I) levels were measured after 24 days, in hypertensive and sham-operated animals. In separate subgroups of these animals, the effect of intracerebroventricular administration of captopril on the parameters listed was studied. The results showed high ang-I levels in 2 KIC rats as compared to controls (P less than 0.05). Captopril administration (500 micrograms/50 microliters icv) caused a fall in BP and increase in brainstem ang-I levels (P less than 0.01). In control animals, however, captopril produced a rise in BP without any significant change in brainstem ang-I levels. Peripheral plasma renin activity was normal, despite significant sodium retention in 2 KIC rats. The results are suggestive of activation of brainstem renin-angiotensin system (RAS) in chronic 2 KIC hypertension.