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This study was aimed to explore underlying mechanism(s) of cardiovascular effects of piperine. Intravenous administration of piperine caused a dose-dependent (1 to 10 mg/kg) decrease in mean arterial pressure (MAP) in normotensive anesthetized rats; the next higher dose (30 mg/kg) did not cause any further change in MAP. The fall in blood pressure (BP) was followed by small increase in MAP after each dose. In Langendorrf's rabbit heart preparation, piperine caused partial inhibition and verapamil caused complete inhibition of force and rate of ventricular contractions and coronary flow. In rabbit aortic rings, piperine inhibited high K+ (80 mM) precontractions and partially inhibited phenylephrine (PE), suggesting Ca2+ channel blockade (CCB), which was further confirmed when pretreatment of tissues with piperine caused rightward shift in Ca2+ concentration-response curves, similar to verapamil. In Ca2+-free medium, piperine (1 to 30 microM) exhibited vasoconstrictor effect. In rat aorta, piperine demonstrated endothelium-independent vasodilator effect and was more potent against high K+ precontractions than PE. In bovine coronary artery preparations, piperine inhibited high K+ precontractions completely. These data indicate that piperine possesses a blood pressure-lowering effect mediated possibly through CCB, while consistent decrease in BP was restricted by associated vasoconstrictor effect. Additionally, species selectivity exists in the CCB effect of piperine.

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BackgroundHypertension has been recognized as a global health concern for developing countries and is scarcely described in many of these countries. In Pakistan, few population-based surveys evaluated the prevalence of hypertension and there is no current nationally representative study (the latest nationwide survey was conducted more than two decades ago). Objective: The goal of the current study was to estimate the pooled prevalence of hypertension in Pakistani population using meta-analysis approach.MethodsWe searched the published literature using PubMed, Google and Scopus supplemented by a manual search of bibliographies of retrieved articles for population studies providing estimates on the prevalence of hypertension between 1990 and 2017. Studies were included if they defined hypertension as ≥140/90 mmHg and conducted in adults (≥15 years). From the extracted results, the heterogeneity index of the studies was determined using Chi-squared I2 tests and on the basis of heterogeneity, a fixed or random effect model was used to estimates the pooled prevalence of hypertension. Meta-regression was performed to determine those factor of generating heterogeneity.ResultsOf a total of 1240 articles, 18 studies comprising 42,618 participants met the eligibility criteria. The overall pooled prevalence of hypertension was 26.34% (25.93%, 26.75%). Subgroup analysis showed higher urban prevalence 26.61% (21.80%, 31.42%) than the rural dwellers 21.03% (10.18%, 31.87%). The prevalence by decade in 1990s was 19.55% (18.07%, 21.05%), in 2000s 23.95% (16.60%, 31.30%) and in 2010s 29.95% (24.13%, 35.77%). Similarly, the pooled prevalence was 24.99% (19.70%, 30.28%) in males and 24.76% (16.76%, 32.76%) in females. We recorded high burden of hypertension among the adult Pakistanis when compared to the data published in local and international journals 23.32% (18.9%, 27.74%) and 27.44% (20.97%, 33.91%). We also found differences in the prevalence of hypertension among small, medium and large studies.ConclusionComparing data from previous studies in Pakistan, we found a higher prevalence in urban areas and among males. The prevalence over time is likely to increase faster, further our results underscore the importance of good quality long-term studies that will help to understand hypertension better and implement effective prevention and management programs.