ACE gene dosage determines additional autonomic dysfunction and increases renal angiotensin II levels in diabetic mice

Single nucleotide polymorphism (SNP) rs4291 of the angiotensin-converting enzyme (ACE) gene is associated with the response to losartan treatment in hypertensive patients

Arterial hypertension is characterized by systolic pressure ≥ 140 mmHg and/or diastolic pressure ≥ 90 mmHg and its treatment consists of the use of antihypertensive drugs, as losartan and hydrochlorothiazide. Blood pressure is regulated by angiotensin-converting enzyme (ACE) and polymorphisms in the ACE gene are associated to a greater predisposition to hypertension and response to treatment. The aim of this study was to evaluate the association of genetic polymorphisms of ACE rs4363, rs4291 and rs4335 and the response to antihypertensive drugs in hypertensive patients from Ouro Preto/MG, Brazil. A case-control study was carried out with 87 hypertensive patients being treated with losartan and 75 with hydrochlorothiazide, who answered a questionnaire and had blood samples collected. Biochemical analyzes were performed on serum using UV/Vis spectrophotometry and identification of ACE variants rs4363, rs4291 and rs4335 was performed by real-time PCR using the TaqMan® system. Univariate logistic regression test was performed to compare categorical data in STATA 13.0 software. The results showed that there was an influence of ACE polymorphisms on the response to losartan, demonstrating that AT or TT genotypes of rs4291 were more frequent in the group of controlled AH (54.9%), indicating that these individuals are 2.8 times more likely to of being controlled AH (95% CI 1.12-6.80, p. =0.026) compared to those with AA genotype. In contrast, no influence of ACE polymorphisms on the response to hydrochlorothiazide was observed. In conclusion, the presence of the T allele of the rs4291 variant was associated to controled blood pressure when losartan was used as an antihypertensive agent. These results show the importance of pharmacogenetic studies to detect genetic characteristics, enabling therapeutic individuality and reducing costs for the healthcare system.

Angiotensin-converting enzyme insertion/deletion (I/D) gene polymorphism in Iraqi type 2 diabetic patients: association with the risk of cardiac autonomic neuropathy

Background

Studies have shown a direct association between angiotensin-converting enzyme (ACE) and diabetic neuropathies. As such, ACE gene polymorphisms could be a risk factor for cardiac autonomic neuropathy (CAN) in patients with diabetes. The objective of our study was to investigate the association of the ACE I/D gene polymorphism with the development of CAN in Iraqi patients with type 2 diabetes mellitus (T2DM).

Results

This is a cross-sectional study that included 142 patients with T2DM comprising 62 males and 80 females, and 100 volunteers served as a healthy control group. Cardiac autonomic functions were tested using four standard Ewing’s noninvasive tests. Blood samples were taken for genetic evaluation of an ACE gene I/D polymorphism.

Analyzing ACE gene polymorphism revealed that the D allele was far more frequent among patients with diabetes than healthy control subjects (76.07% vs. 62.67%). The frequency of I/I, I/D, and D/D genotypes in patients with diabetes was 8.55%, 30.77%, and 60.68%, respectively, compared with 18.67%, 37.33%, and 44%, respectively, in controls with a significant difference in mutant homozygous genotype. However, there were no significant differences in these genotypes between patients with and without CAN. Although patients with CAN showed a much higher frequency of D allele than those without CAN, the difference did not reach significance (p = 0.054).

Conclusion

The DD genotype and D allele of the ACE I/D gene polymorphism can be a risk factor for T2DM, and the D allele of this polymorphism can even be associated with the development of CAN in these patients.

Effect of novel GPCR ligands on blood pressure and vascular homeostasis

Maintenance of normal blood pressure under conditions of drug treatment is a measure of system-wide neuro-hormonal controls and electrolyte/fluid volume homeostasis in the body. With increased interest in designing and evaluating novel drugs that may functionally select or allosterically modulate specific GPCR signaling pathways, techniques that allow us to measure acute and long-term effects on blood pressure are very important. Therefore, this chapter describes techniques to measure acute and long-term impact of novel GPCR ligands on blood pressure regulation. We will use the angiotensin type 1 receptor, a powerful blood pressure regulating GPCR, in detailing the methodology. Normal blood pressure maintenance depends upon dynamic modulation of angiotensin type 1 receptor activity by the hormone peptide angiotensin II. Chronic activation of angiotensin type 1 receptor creates hypertension and related cardiovascular disease states which are treated with angiotensin type 1 receptor blockers (ARBs). Thus, a prototype for evaluation of blood pressure control under experimental evaluation of novel drugs.