Emerging Role of Calcium-Activated Potassium Channel in the Regulation of Cell Viability Following Potassium Ions Challenge in HEK293 Cells and Pharmacological Modulation.

Emerging Role of Calcium-Activated Potassium Channel in the Regulation of Cell Viability Following Potassium Ions Challenge in HEK293 Cells and Pharmacological Modulation.

PLoS One. 2013; 8(7): e69551
Tricarico D, Mele A, Calzolaro S, Cannone G, Camerino GM, Dinardo MM, Latorre R, Conte Camerino D

Emerging evidences suggest that Ca(2+)activated-K(+)-(BK) channel is involved in the regulation of cell viability. The changes of the cell viability observed under hyperkalemia (15 mEq/L) or hypokalemia (0.55 mEq/L) conditions were investigated in HEK293 cells expressing the hslo subunit (hslo-HEK293) in the presence or absence of BK channel modulators. The BK channel openers(10(-11)-10(-3)M) were: acetazolamide(ACTZ), Dichlorphenamide(DCP), methazolamide(MTZ), bendroflumethiazide(BFT), ethoxzolamide(ETX), hydrochlorthiazide(HCT), quercetin(QUERC), resveratrol(RESV) and NS1619; and the BK channel blockers(2×10(-7)M-5×10(-3)M) were: tetraethylammonium(TEA), iberiotoxin(IbTx) and charybdotoxin(ChTX). Experiments on cell viability and channel currents were performed using cell counting kit-8 and patch-clamp techniques, respectively. Hslo whole-cell current was potentiated by BK channel openers with different potency and efficacy in hslo-HEK293. The efficacy ranking of the openers at -60 mV(Vm) was BFT> ACTZ >DCP ?RESV? ETX> NS1619> MTZ? QUERC; HCT was not effective. Cell viability after 24 h of incubation under hyperkalemia was enhanced by 82+6% and 33+7% in hslo-HEK293 cells and HEK293 cells, respectively. IbTx, ChTX and TEA enhanced cell viability in hslo-HEK293. BK openers prevented the enhancement of the cell viability induced by hyperkalemia or IbTx in hslo-HEK293 showing an efficacy which was comparable with that observed as BK openers. BK channel modulators failed to affect cell currents and viability under hyperkalemia conditions in the absence of hslo subunit. In contrast, under hypokalemia cell viability was reduced by -22+4% and -23+6% in hslo-HEK293 and HEK293 cells, respectively; the BK channel modulators failed to affect this parameter in these cells. In conclusion, BK channel regulates cell viability under hyperkalemia but not hypokalemia conditions. BFT and ACTZ were the most potent drugs either in activating the BK current and in preventing the cell proliferation induced by hyperkalemia. These findings may have relevance in disorders associated with abnormal K(+) ion homeostasis including periodic paralysis and myotonia. HubMed – drug

Multimechanistic antifibrotic effect of biochanin a in rats: implications of proinflammatory and profibrogenic mediators.

PLoS One. 2013; 8(7): e69276
Breikaa RM, Algandaby MM, El-Demerdash E, Abdel-Naim AB

Biochanin A (BCA) is an isoflavone found in red clover and peanuts. Recently, it drew much attention as a promising anticancer and antioxidant. Due to its diversity in pharmacological actions, we were encouraged to investigate its potential as an antifibrotic, elucidating the different molecular mechanisms involved.Rats were pretreated with BCA, then injected with carbon tetrachloride (CCl4) for 6 weeks. Changes in liver weight and histology were examined and levels of aspartate and alanine aminotransferases, cholesterol, triglycerides, alkaline phosphatase and total bilirubin measured. To assess hepatic efficiency, indocyanine green was injected and its clearance calculated and albumin, total proteins and insulin-like growth factor-1 expression were measured. Cytochrome P4502E1 activity, cytochrome P4501A1 expression, in addition to sulfotransferase1A1 expression were determined to deduce the effect of BCA on hepatic metabolism. As oxidative stress markers, lipid peroxides levels, reduced glutathione, superoxide dismutase and catalase activities, as well as the total antioxidant capacity, were assessed. Nitric oxide, inducible nitric oxide synthase and cyclooxygenase-2 were used as indicators of the inflammatory response. Signaling pathways involving tumor necrosis factor-alpha, nuclear factor-kappa B, transforming growth factor-beta1, matrix metalloproteinase-9 and alpha-smooth muscle actin were investigated accordingly. Extent of fibrosis was examined by Masson’s stain and measuring hydroxyproline levels.BCA pretreatment significantly protected against the chronic damage of CCl4. Liver injury, oxidative stress, inflammation and fibrosis markers decreased, while hepatic efficiency improved.Our findings suggested that BCA administration protects against fibrotic complications, a property that can be contributed to the multimechanistic approach of the drug. HubMed – drug

Estimating the prevalence of opioid diversion by “doctor shoppers” in the United States.

PLoS One. 2013; 8(7): e69241
McDonald DC, Carlson KE

Abuse of prescription opioid analgesics is a serious threat to public health, resulting in rising numbers of overdose deaths and admissions to emergency departments and treatment facilities. Absent adequate patient information systems, “doctor shopping” patients can obtain multiple opioid prescriptions for nonmedical use from different unknowing physicians. Our study estimates the prevalence of doctor shopping in the US and the amounts and types of opioids involved.The sample included records for 146.1 million opioid prescriptions dispensed during 2008 by 76% of US retail pharmacies. Prescriptions were linked to unique patients and weighted to estimate all prescriptions and patients in the nation. Finite mixture models were used to estimate different latent patient populations having different patterns of using prescribers. On average, patients in the extreme outlying population (0.7% of purchasers), presumed to be doctor shoppers, obtained 32 opioid prescriptions from 10 different prescribers. They bought 1.9% of all opioid prescriptions, constituting 4% of weighed amounts dispensed.Our data did not provide information to make a clinical diagnosis of individuals. Very few of these patients can be classified with certainty as diverting drugs for nonmedical purposes. However, even patients with legitimate medical need for opioids who use large numbers of prescribers may signal dangerously uncoordinated care. To close the information gap that makes doctor shopping and uncoordinated care possible, states have created prescription drug monitoring programs to collect records of scheduled drugs dispensed, but the majority of physicians do not access this information. To facilitate use by busy practitioners, most monitoring programs should improve access and response time, scan prescription data to flag suspicious purchasing patterns and alert physicians and pharmacists. Physicians could also prevent doctor shopping by adopting procedures to screen new patients for their risk of abuse and to monitor patients’ adherence to prescribed treatments. HubMed – drug

Cardioprotective effects of a novel hydrogen sulfide agent-controlled release formulation of s-propargyl-cysteine on heart failure rats and molecular mechanisms.

PLoS One. 2013; 8(7): e69205
Huang C, Kan J, Liu X, Ma F, Tran BH, Zou Y, Wang S, Zhu YZ

Heart failure (HF) is one of the most serious diseases worldwide. S-propargyl-cysteine (SPRC), a novel modulator of endogenous hydrogen sulfide, is proved to be able to protect against acute myocardial ischemia. In order to produce more stable and sustainable hydrogen sulfide, we used controlled release formulation of SPRC (CR-SPRC) to elucidate possible cardioprotective effects on HF rats and investigate involved mechanisms on apoptosis and oxidation.Left coronary artery was occluded to induce HF model of rat. The survival rats were randomly divided into 7 groups after 24 hours and treated with drugs for 6 weeks. Echocardiographic indexes were recorded to determine cardiac function. TTC staining was performed to determine infarct size. Plasmatic level of hydrogen sulfide was detected by modified sulfide electrode. Activity of enzyme and expression of protein were determined by colorimetry and Western blot, respectively.The cardioprotective effects of CR-SPRC on HF rats were confirmed by significant reduction of infarct size and improvement of cardiac function, with better effects compared to normal SPRC. CR-SPRC modulated antioxidant defenses by preserving levels of GSH, CAT and SOD and reducing CK leakage. In addition, CR-SPRC elevated ratio of Bcl-2/Bax and inhibited activity of caspases to protect against myocardial apoptosis. The cardioprotective effects of CR-SPRC were mediated by hydrogen sulfide.All experiment data indicated cardioprotective effects of CR-SPRC on HF rats. More importantly, CR-SPRC exerted better effects than normal SPRC in all respects, providing a new perspective on hydrogen sulfide-mediated drug therapy. HubMed – drug