Oestrogen attenuates coronary vasoconstriction after angioplasty: role of endothelin-1

Effect of nicorandil on proteinuria in well controlled hypertensive patients

OBJECTIVE

Proteinuria is an important risk factor for cardiovascular and renal morbidity and mortality. The effect of nicorandil on proteinuria in hypertensive patients well controlled by antihypertensive agents containing a low dose of valsartan has not been studied.

PATIENTS AND METHODS

A total of 136 proteinuric (300-3000 mg/day), valsartan-treated hypertensive patients with blood pressure less than 140/90 mmHg were randomized into three groups to receive placebo, isosorbide dinitrate (30 mg/day), or nicorandil (15 mg/day) for 6 months.

RESULTS

The average dose of valsartan given to the patients was similar in the three groups. Creatinine clearance remained stable throughout the study in the three groups. Nicorandil, but not isosorbide dinitrate, significantly reduced proteinuria by 44% after 6 months (P < 0.0001). Urinary endothelin-1 levels significantly decreased after administration of nicorandil (P = 0.002), whereas placebo and isosorbide dinitrate had no effect. Urinary excretion of endothelin-1 was significantly correlated with improvement in urinary protein excretion in nicorandil-treated patients (r = 0.69, P < 0.0001). The urinary excretion of retinol-binding protein decreased after nicorandil administration, probably reflecting an improvement in tubular function. In contrast, the urinary excretion of immunoglobulin G did not change significantly throughout the study in the three groups. Multivariate analysis revealed that proteinuria was only significantly correlated with the use of nicorandil (model adjusted r = 0.35, P < 0.0001).

CONCLUSION

The addition of nicorandil to treatment for patients with well controlled hypertension may have an additive effect on reducing proteinuria independent of hemodynamics and nitric oxide effects, possibly through inhibiting renal endothelin-1 synthesis and improving tubular function.

The role of estrogen in cardiovascular disease

Cardiovascular disease is the number one cause of death among women, accounting for nearly 50% of female deaths. Statistics show that women on average develop cardiovascular disease 10 to 15 years later in life than men, and that the risk may increase after menopause. This observation has led to much speculation as to what physiological change(s) associated with menopause is responsible for the higher risk of atherosclerosis. Estrogen, with its potential as a cardioprotective agent and as an immunomodulator of the inflammatory response in atherosclerosis, has received the most attention. Understanding the mechanisms that lead to these differences may allow beneficial therapeutic intervention to enhance this effect in females and evoke this protection in males. This review will do the following: (1) characterize mechanisms of atherosclerosis, (2) explore the role of estrogen-replacement therapy, (3) define the effect of gender on inflammation, (4) compare and contrast the effects of estrogen and testosterone on endothelial functional, and (5) suggest mechanistic based therapeutic opportunities.

Estrogen and testosterone have opposing effects on chronic cardiac remodeling and function in mice with myocardial infarction

Premenopausal women are much less prone to develop cardiovascular disease than men of similar age, but this advantage no longer applies after menopause. We previously found that male mice have a significantly higher rate of cardiac rupture than females during the acute phase of myocardial infarction (MI); however, the effects of sexual hormones on chronic remodeling are unknown. We hypothesized that estrogen (E) may protect the heart from chronic remodeling and deterioration of function post-MI, whereas testosterone (T) may have adverse effects. Mice (4 wk old) of both genders were divided into four groups: female groups consisted of 1) sham ovariectomy (S-Ovx) + placebo (P) (S-Ovx + P), 2) S-Ovx + T, 3) Ovx + P, and 4) Ovx + T; and male groups consisted of 1) sham castration (S-Cas)+ P (S-Cas + P), 2) S-Cas + 17beta-estradiol (E), 3) Cas + P, and 4) Cas + E. MI was induced 6 wk later. Echocardiography was performed to assess cardiac function and left ventricular dimensions (LVD). Myocyte cross-sectional area (MCSA) was measured at the end of the study. In females, both testosterone and ovariectomy decreased ejection fraction (EF) and increased LVD, and when combined they aggravated cardiac function and remodeling further. Testosterone significantly increased MCSA. In males, castration or estrogen increased EF and reduced LVD, whereas castration significantly reduced MCSA. Our data suggest that estrogen prevents deterioration of cardiac function and remodeling after MI, but testosterone worsens cardiac dysfunction and remodeling and has a pronounced effect when estrogen levels are reduced.

Effect of estradiol administration on splanchnic perfusion after trauma-hemorrhage and sepsis

PURPOSE OF REVIEW

This review focuses on the latest mechanistic understanding of the effects of estradiol on the splanchnic circulation and the possibility of estradiol treatment as an adjunct for the treatment of trauma-hemorrhage and sepsis.

RECENT FINDINGS

Systemic hypotension induced by shock accompanies marked alterations in blood flow to various organs. Decreased splanchnic perfusion is frequently observed after insults, such as severe hemorrhage or sepsis, which leads to the destruction of the intestinal mucosal barrier and hepatic dysfunction. Studies suggest that estradiol acts as a facilitator of the intestinal blood flow via the increased production of nitric oxide, decreased production of vasoconstrictors, attenuated neutrophil adhesion, and decreased formation of oxygen free radicals.

SUMMARY

Trauma-hemorrhage results in decreased circulating blood volume. In contrast, sepsis is an inflammatory state mainly mediated by bacterial products. However, these divergent insults show similar pathophysiologic alterations in terms of the splanchnic circulation. Because estradiol effectively protects the organs from circulatory failure after various adverse circulatory conditions, many studies are being performed to clarify the molecular mechanism of estradiol action with regard to tissue circulation. Estradiol improves the macro- and microcirculation of the splanchnic organs by multiple mechanisms. Nonetheless, it remains unclear which mechanism plays the most important role in the treatment of trauma-hemorrhage and sepsis. Additional studies are required to elucidate the precise mechanism of estradiol action and to determine the usefulness of estradiol treatment for severe hemorrhage and sepsis in patients.

Differential role of K(ATP) channels activated by conjugated estrogens in the regulation of myocardial and coronary protective effects

BACKGROUND

We have demonstrated that estrogen can reduce myocardial injury in ischemia-reperfusion via activation of ATP-sensitive potassium (K(ATP)) channels. We sought to determine whether the protective effect of estrogen extends to epicardial coronary artery with attenuated vasoconstriction in patients after angioplasty by activation of such channels.

METHODS AND RESULTS

The study was designed to prospectively investigate 41 consecutive patients scheduled for elective coronary angioplasty. Pretreatment with estrogen limited myocardial ischemia during coronary occlusion and attenuated postangioplasty coronary vasoconstriction at the dilated and distal segments. An inhibitor of K(ATP) channels, glibenclamide, did not affect coronary vasomotor response, although it abolished the beneficial effect of estrogen on myocardial ischemia. Patients to whom estrogen was administered after the second balloon deflation experienced a similar magnitude of myocardial ischemia as controls but showed significantly attenuated vasoconstriction compared with controls (P=0.0001). Endothelin-1 levels from the great cardiac vein rose significantly from 1.9+/-0.4 to 3.1+/-0.6 pg/mL (P=0.001) 15 minutes after angioplasty in the control group; this was attenuated after estrogen was administered. Significant correlation was found between the changes in coronary vasomotion of the dilated segment and endothelin-1 levels (r=0.65, P<0.0001).

CONCLUSIONS

These results demonstrate that estrogen is protective against both myocardial ischemia and coronary vasoconstriction through different mechanisms. The myocardial effect of estrogen was abolished by glibenclamide, which suggests that the cardioprotective effect of estrogen may result from activation of K(ATP) channels. In contrast, estrogen-induced attenuated vasoconstriction is associated with an attenuated release of endothelin-1, independent of K(ATP) activation.

Effect of pravastatin on proteinuria in patients with well-controlled hypertension

Proteinuria is an important risk factor for cardiovascular and renal morbidity and mortality. The effects of 3-hydroxy-3-methyglutaryl coenzyme A reductase inhibitor (statin) therapy on proteinuria in normolipidemic patients with well-controlled hypertension have not been studied. A total of 63 normolipidemic (total cholesterol <240 mg/dL) and proteinuric (300 to 3000 mg/d) patients with well-controlled blood pressure (<140/90 mm Hg) were randomized to receive either placebo (n=32) or pravastatin (10 mg/d; n=31) after a 3-month placebo period. Pravastatin lowered proteinuria after 6 months by 54% (P<0.0001). Creatinine clearance was stable throughout the study in the 2 groups. Despite unchanged plasma endothelin-1 levels throughout the study, urinary excretion of the peptide was decreased and significantly correlated with improvement in urinary protein excretion in pravastatin-treated patients (r=0.64, P=0.001). The urinary excretion of retinol-binding protein decreased after pravastatin administration, probably reflecting an improvement in tubular function. In contrast, the urinary excretion of IgG did not change significantly throughout the study in either group. Multivariate analysis revealed that proteinuria was only significantly correlated with statin use (P<0.0001, R2= 0.66). Linear regression analysis in the statin-treated group did not show any correlation between changes in lipid profiles and proteinuria regression. Thus, in addition to their primary function of antilipidemia, the addition of pravastatin to treatment for well-controlled hypertension may have an additive effect on reducing proteinuria independent of hemodynamics and lipid-lowering effects, possibly through inhibiting renal endothelin-1 synthesis and improving tubular function.