Role of prostaglandins in the renal handling of a salt load in essential hypertension

Application of microRNAs in diagnosis and treatment of cardiovascular disease

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide. Innovative, more stringent diagnostic and prognostic biomarkers and effective treatment options are needed to lessen its burden. In recent years, microRNAs have emerged as master regulators of gene expression - they bind to complementary sequences within the mRNAs of their target genes and inhibit their expression by either mRNA degradation or translational repression. microRNAs have been implicated in all major cellular processes, including cell cycle, differentiation and metabolism. Their unique mode of action, fine-tuning gene expression rather than turning genes on/off, and their ability to simultaneously regulate multiple elements of relevant pathways makes them enticing potential biomarkers and therapeutic targets. Indeed, cardiovascular patients have specific patterns of circulating microRNA levels, often early in the disease process. This article provides a systematic overview of the role of microRNAs in the pathophysiology, diagnosis and treatment of CVD.

Effect of high-dose ibuprofen on 24-hour blood pressure in healthy women

The nonsteroidal antiinflammatory drug (NSAID) indomethacin has been shown to increase blood pressure in normotensive individuals. The effect of other NSAID on blood pressure has not been as well studied. We evaluated the effects of ibuprofen, an NSAID currently available without a prescription, on 24-hour ambulatory blood pressure in ten young, healthy, normotensive women. Using a randomized, crossover, double-blind design, subjects received ibuprofen 800 mg and a placebo identical in appearance to ibuprofen three times a day for eight days with a washout period between regimens. Subjects were instructed to follow a no-added salt diet during the study. Twenty-four-hour blood pressure monitoring and 24-hour urine collection for prostaglandin E2, creatinine, and sodium were performed on days 1 and 8 of each study week. Tablet counts and a 40 percent reduction in urinary prostaglandin E2 documented compliance with ibuprofen. Ibuprofen had no significant effect on systolic or diastolic blood pressure at any hour during the 24-hour period. Mean blood pressure for the 24-hour period was 112/73 and 111/73 mm Hg on day 1 and 111/73 and 112/73 mm Hg on day 8 for placebo and ibuprofen, respectively. We conclude that ibuprofen at doses as high as 2400 mg/d for up to seven days has no effect on blood pressure in normotensive women. Further studies are needed in hypertensive subjects.

Effects of nonsteroidal anti-inflammatory drugs in healthy subjects

Nonsteroidal anti-inflammatory drugs inhibit cyclo-oxygenase activity and thereby reduce prostaglandin synthesis. Studies in humans have used these cyclo-oxygenase inhibitors to examine the role of prostaglandins in controlling renal function. Although short-term studies have demonstrated reductions in effective renal plasma flow, glomerular filtration rate, urinary sodium excretion, and plasma renin activity, long-term administration of nonsteroidal anti-inflammatory drugs does not result in significant or clinically important changes in renal function in normal human subjects. If healthy volunteers are placed on low-sodium diets or treated with diuretics, both renal hemodynamics and salt and water excretion can become prostaglandin-dependent. Studies in normal subjects suggest that sulindac, a nonsteroidal anti-inflammatory drug that undergoes biotransformation in the kidney, does not inhibit renal prostaglandin synthesis or urinary sodium excretion under basal conditions but may impair furosemide-stimulated prostaglandin synthesis and changes in renal function. Doses of sulindac that spare basal renal cyclo-oxygenase do inhibit extrarenal cyclo-oxygenase. The mechanism responsible for this biochemical selectivity of sulindac is not related to a differential sensitivity of the renal cyclo-oxygenase to the active metabolite of sulindac, sulindac sulfide. Sulindac sulfide, in concentrations as low as 1 nM, was equipotent to indomethacin as an inhibitor of prostaglandin E2 synthesis in primary cultures of three renal cell lines. Appropriate clinical use of all nonsteroidal anti-inflammatory drugs, including sulindac, requires careful consideration of risk factors that predispose to nephrotoxicity and careful monitoring when administered to patients at risk.

Inhibition of renal prostaglandin synthesis in man: methodological and clinical implications

Integrity of renal prostaglandin synthesis is necessary to maintain renal cortical and medullary function in patients with kidney, heart and liver disease. A comparison of the biochemical effects of various non-steroidal anti-inflammatory drugs (NSAIDs) necessitates that renal prostaglandin synthesis, as reflected by urinary immunoreactive prostaglandin excretion, be assessed with proper attention to problems created by seminal fluid contamination, inadequate chromatographic separation of samples, and largely unknown cross reactivities of systemic eicosanoid metabolites with antibodies raised against primary prostaglandins. Most, but not all, clinical studies support the observation that conventional doses of sulindac, administered orally, do not inhibit renal prostaglandin synthesis or alter renal function. Caution is in order, however, about the use of any NSAID, including sulindac at conventional dosage, in patients with severe liver disease as the plasma levels of sulindac sulfide are increased and prolonged compared to patients with normal hepatic function. Furosemide-induced natriuresis is probably not prostaglandin-mediated, in contrast to increased in renal blood flow and renin release. Some NSAIDs can attenuate the efficacy of antihypertensive therapy. Inasmuch as sulindac does inhibit systemic vascular prostacyclin production, its lack of hypertensive effect vis-a-vis other NSAIDs argues in favor of the importance of intrarenal prostaglandin-dependent mechanisms in mediating the hemodynamic effects of non-selective cyclooxygenase inhibitors.