Journal of Hypertension: Open Access

Cardiotonic steroids play a key role in sodium excretion in response to volume expansion. Their effect is mediated through their binding to the Na/K-ATPase, a membrane ion transporter which has recently been found to serve as scaffolding and signaling protein. These scaffolding and signaling functions not only stimulate natriuresis through the endocytosis of key ion transporters, namely the sodium proton antiporter isoform 3 (NHE3) and itself, but also produces pro-fibrotic effects. The focus of this editorial is to the tradeoff this creates between natriuresis in the short term and progression of cardiac and renal fibrosis in the long term.

Gender difference has been suggested as a risk factor for developing cardiovascular and renal diseases in humans and experimental animals. As a major sex hormone, progesterone was reported to compete with cardiotonic steroid binding to Na/K-ATPase. Our previous publication demonstrated that cardiotonic steroids (e.g., marinobufagenin) play an important role in the development of experimental uremic cardiomyopathy. We also observed that the putative mineralocorticoid antagonists, spironolactone and its major metabolite canrenone, antagonize binding of cardiotonic steroids to Na/K-ATPase in a competitive manner and also ameliorate experimental uremic cardiomyopathy induced by partial nephrectomy. In the following studies, we noted that progesterone displayed competitive inhibition of cardiotonic steroid binding to Na/K-ATPase and partially inhibited collagen synthesis induced by marinobufagenin in cultured cardiac fibroblasts. Therefore, we sought to examine whether female rats displayed less uremic cardiomyopathy than male rats when subjected to partial nephrectomy. Although partial nephrectomy caused the induction of smaller increases in blood pressure of female rats, they appeared to be similarly susceptible to cardiac remodeling induced by partial nephrectomy in terms of hypertrophy and fibrosis as age-matched male rats. The possible explanations for our findings are therefore discussed.

Background: Overweight and obesity (overweight/obesity) is associated with hypertension. Low- and middleincome countries are experiencing an obesity epidemic. There is growing evidence that the epidemic is on the increase in urban settings of developing countries. However, there is scanty information on the magnitude of this epidemic and its correlates in rural settings. The objective of the current study was to establish levels of overweight/obesity and its correlates in rural areas of Zambia. Designing interventions based on the correlates for overweight/obesity to reduce its prevalence may in turn lead to a reduction in the prevalence of hypertension.

Methods: Cross sectional studies using a modified WHO Stepwise questionnaire were conducted. Logistic regression analyses were used to determine factors that were associated with overweight/obesity. Unadjusted odds ratios (OR) and adjusted odds ratios (AOR) and their 95% confidence intervals are reported.

Results: Totals of 895 participants from Kaoma and 1198 from Kasama took part in the study. Altogether, 7.6% of the participants were overweight and 2.5% were obese, with a combined prevalence of overweight/obesity of 10.1%. Factors that were independently associated with overweight/obesity were sex, education, vegetable consumption, smoking and hypertension. Female participants were 78% (AOR=1.78, 95% CI [1.46, 2.17]) more like to be overweight/ obese compared to males. Participants with secondary or higher education level were 2.04 (95% CI [1.56, 2.67]) times more likely to be overweight/obese compared to participants with lower levels of education. Participants who consumed vegetables 5 to 7 days in a week were 35% (AOR=1.35, 95% CI [1.06, 1.72]) more likely to be overweight/ obese compared to participants who ate vegetables less than 5 days in a week. Non smokers were 2.06 (95% CI [1.42, 2.98]) times more likely to be overweight/obese than smokers. Participants who were non hypertensive were 30% (AOR=0.70, 95% CI [0.59, 0.82]) less likely to be overweight/obese compared to participants who were hypertensive.

Conclusions: Prevalence of overweight/obesity was low and this is the time to start instituting interventions to control the obesity epidemic in rural districts of Zambia.

Hypertension is a common, undertreated disease and a major risk factor for cardiovascular, cerebrovascular and renal disease. As many as 20-30% of hypertensive patients have resistant hypertension, defined as uncontrolled blood pressure despite 3 or more antihypertensive drugs including a diuretic, typically combined with a calcium-channel blocker and an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker. Patients with resistant hypertension can often be controlled by adding a mineralocorticoid receptor antagonist and/or vasodilating beta-blocker. A significant number of patients will have a treatable secondary cause of resistant hypertension such as obesity, sleep apnea, renal insufficiency, primary aldosteronism or renal artery stenosis. For patients whose hypertension is refractory to preferred antihypertensives, use of third-line antihypertensives such as sympatholytics or vasodilators may be effective but consideration should be given to investigational device-based antihypertensive therapies. Renal artery angioplasty/ stenting can be useful in selected cases of renal artery stenosis, while renal sympathetic denervation holds promise for resistant essential hypertension.

A Case report about a patient with severe pulmonary hypertension which during the investigation non-hepatosplenic schistosomiasis was found, concomitant with pulmonary thromboembolism and Marfan syndrome phenotype is discussed.