Effects of streptozotocin-induced diabetes on the pharmacology of rat conduit and resistance intrapulmonary arteries

Abstract Background Poor control of blood glucose in diabetes is known to promote vascular dysfunction and hypertension. Diabetes was recently shown to be linked to an increased prevalence of pulmonary hypertension. The aim of this study was to determine how the pharmacological reactivity of intrapulmonary arteries is altered in a rat model of diabetes. Methods Diabetes was induced in rats by the β-cell toxin, streptozotocin (STZ, 60 mg/kg), and isolated conduit and resistance intrapulmonary arteries studied 3–4 months later. Isometric tension responses to the vasoconstrictors phenylephrine, serotonin and PGF2α, and the vasodilators carbachol and glyceryl trinitrate, were compared in STZ-treated rats and age-matched controls. Results STZ-induced diabetes significantly blunted the maximum response of conduit, but not resistance pulmonary arteries to phenylephrine and serotonin, without a change in pEC50. Agonist responses were differentially reduced, with serotonin (46% smaller) affected more than phenylephrine (32% smaller) and responses to PGF2α unaltered. Vasoconstriction caused by K+-induced depolarisation remained normal in diabetic rats. Endothelium-dependent dilation to carbachol and endothelium-independent dilation to glyceryl trinitrate were also unaffected. Conclusion The small resistance pulmonary arteries are relatively resistant to STZ-induced diabetes. The impaired constrictor responsiveness of conduit vessels was agonist dependent, suggesting possible loss of receptor expression or function. The observed effects cannot account for pulmonary hypertension in diabetes, rather the impaired reactivity to vasoconstrictors would counteract the development of pulmonary hypertensive disease.</p

Cellular and molecular targets of menthol actions

© 2017 Oz, El Nebrisi, Yang, Howarth and Al Kury. Menthol belongs to monoterpene class of a structurally diverse group of phytochemicals found in plant-derived essential oils. Menthol is widely used in pharmaceuticals, confectionary, oral hygiene products, pesticides, cosmetics, and as a flavoring agent. In addition, menthol is known to have antioxidant, anti-inflammatory, and analgesic effects. Recently, there has been renewed awareness in comprehending the biological and pharmacological effects of menthol. TRP channels have been demonstrated to mediate the cooling actions of menthol. There has been new evidence demonstrating that menthol can significantly influence the functional characteristics of a number of different kinds of ligand and voltage-gated ion channels, indicating that at least some of the biological and pharmacological effects of menthol can be mediated by alterations in cellular excitability. In this article, we examine the results of earlier studies on the actions of menthol with voltage and ligand-gated ion channels

eosinophil derived neurotoxin and clinical outcomes with mepolizumab in severe eosinophilic asthma

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Curcumin potentiates the function of human α \u3csub\u3e7\u3c/sub\u3e -nicotinic acetylcholine receptors expressed in SH-EP1 cells

© 2018 Elsevier Ltd Effects of curcumin, a biologically active ingredient of turmeric, were tested on the Ca 2+ transients induced by the activation of α 7 subunit of the human nicotinic acetylcholine (α 7 nACh) receptor expressed in SH-EP1 cells. Curcumin caused a significant potentiation of choline (1 mM)-induced Ca 2+ transients with an EC 50 value of 133 nM. The potentiating effect of curcumin was not observed in Ca 2+ transients induced by high K + (60 mM) containing solutions or activation of α 4 β 2 nACh receptors and the extent of curcumin potentiation was not altered in the presence of Ca 2+ channel antagonists nifedipine (1 μM), verapamil (1 μM), ω-conotoxin (1 μM), and bepridil (10 μM). Noticeably the effect of curcumin was not observed when curcumin and choline were co-applied without curcumin pre-incubation. The effect of curcumin on choline-induced Ca 2+ transients was not reversed by pre-incubation with inhibitors of protein C, A, and CaM kinases. Metabolites of curcumin such as tetrahydrocurcumin, demethylcurcumin, and didemethylcurcumin also caused potentiation of choline-induced Ca 2+ transients. Notably, specific binding of [ 125 I]-bungarotoxin was not altered in the presence of curcumin. Collectively, our results indicate that curcumin allosterically potentiate the function of the α7-nACh receptor expressed in SH-EP1 cells

Effects of prolactin on ventricular myocyte shortening and calcium transport in the streptozotocin-induced diabetic rat

© 2020 Cardiology; Cell biology; Endocrinology; Molecular Biology; Pathophysiology; Pharmacology; Physiology; prolactin; Diabetes mellitus; heart; Ventricular myocytes; Contraction; Calciu

Hyperglycemia-induced cardiac contractile dysfunction in the diabetic heart

The development of a diabetic cardiomyopathy is a multifactorial process, and evidence is accumulating that defects in intracellular free calcium concentration [Ca2+]i or its homeostasis are related to impaired mechanical performance of the diabetic heart leading to a reduction in contractile dysfunction. Defects in ryanodine receptor, reduced activity of the sarcoplasmic reticulum calcium pump (SERCA) and, along with reduced activity of the sodium-calcium exchanger (NCX) and alterations in myofilament, collectively cause a calcium imbalance within the diabetic cardiomyocytes. This in turn is characterized by cytosolic calcium overloading or elevated diastolic calcium leading to heart failure. Numerous studies have been performed to identify the cellular, subcellular, and molecular derangements in diabetes-induced cardiomyopathy (DCM), but the precise mechanism(s) is still unknown. This review focuses on the mechanism behind DCM, the onset of contractile dysfunction, and the associated changes with special emphasis on hyperglycemia, mitochondrial dysfunction in the diabetic heart. Further, management strategies, including treatment and emerging therapeutic modalities, are discussed

Menthol Binding and Inhibition of a7-Nicotinic Acetylcholine Receptors

Menthol is a common compound in pharmaceutical and commercial products and a popular additive to cigarettes. The molecular targets of menthol remain poorly defined. In this study we show an effect of menthol on the α7 subunit of the nicotinic acetylcholine (nACh) receptor function. Using a two-electrode voltage-clamp technique, menthol was found to reversibly inhibit α7-nACh receptors heterologously expressed in Xenopus oocytes. Inhibition by menthol was not dependent on the membrane potential and did not involve endogenous Ca2+-dependent Cl− channels, since menthol inhibition remained unchanged by intracellular injection of the Ca2+ chelator BAPTA and perfusion with Ca2+-free bathing solution containing Ba2+. Furthermore, increasing ACh concentrations did not reverse menthol inhibition and the specific binding of [125I] α-bungarotoxin was not attenuated by menthol. Studies of α7- nACh receptors endogenously expressed in neural cells demonstrate that menthol attenuates α7 mediated Ca2+ transients in the cell body and neurite. In conclusion, our results suggest that menthol inhibits α7-nACh receptors in a noncompetitive manner

Menthol Inhibits 5-HT 3

The effects of alcohol monoterpene menthol, a major active in-gredient of the peppermint plant, were tested on the function of human 5-hydroxytryptamine type 3 (5-HT3) receptors expressed in Xenopus laevis oocytes. 5-HT (1 mM)-evoked currents recorded by two-electrode voltage-clamp technique were reversibly inhibited bymenthol in a concentration-dependent (IC505 163mM)manner. The effects of menthol developed gradually, reaching a steady-state level within 10–15 minutes and did not involve G-proteins, since GTPgS activity remained unaltered and the effect of menthol was not sensitive to pertussis toxin pretreatment. The actions of menthol were not stereoselective as (2), (1), and racemic menthol inhibited 5-HT3 receptor–mediated currents to the same extent. Menthol inhibition was not altered by intracellular 1,2-bis(o-aminophenoxy)ethane-N,N,N9,N9-tetraacetic acid injections an

Mechanisms of Diabetes Mellitus-Induced Sudden Cardiac Death

More than 450 million people worldwide have diabetes mellitus (DM), a metabolic disorder characterized by an increase in blood glucose level (hyperglycemia) that arises from insufficient insulin secretion or resistance to insulin’s action. More than 70% of individuals with chronic DM will develop cardiovascular diseases (CVDs) including atherosclerosis and coronary artery diseases (CADs), hypertension, cardiac arrhythmias, cardiomyopathy (heart failure), stroke, and chronic kidney disease. A significant number of these individuals will also succumb to sudden cardiac death (SCD). SCD usually occurs in early morning from abnormal heart rhythms or arrhythmias and ventricular fibrillation. When the pumping action of the heart becomes erratic, a reduction in oxygenated blood to the brain leads to unconsciousness and brain damage. SCD is independent of age and sex and positively correlates with impairment in cardiac metabolism, muscle damage, fibrosis, apoptosis, hypertrophy, ischemia, and deranged cation signaling. This review centers on mechanisms by which intracellular cations (Na+, K+, and Ca2+) handling, inflammation, and oxidative and carbonyl stresses due to diabetes-induced hyperglycemia can lead to the deterioration of excitation/contraction coupling (ECC), impaired contractility, arrhythmias, and SCD in DM patients. It also discusses the beneficial effects of exercise training to attenuate the risk of SCD

Social representations of diagnosis in the consultation

Observations of physiotherapy consultations and qualitative interviews with patients were conducted to explore the clinical explanation for sciatic pain. We report three themes which illustrate the contested and negotiated order of the clinical explanation: anchoring, resistance and normalisation. We show using the theory of social representations how the social order in the physiotherapy consultation is maintained, contested and rearticulated. We highlight the importance of agency in patients’ ability to resist the clinical explanation and in turn shape the clinical discourse within the consultation. Social representations offer insights into how the world is viewed by different individuals, in our case physiotherapists and patients with sciatic pain symptoms. The negotiation about the diagnosis reveals the malleable and socially constructed nature of pain and the meaning making process underpinning it. The study has implications for understanding inequalities in the consultation and the key ingredients of consensus