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Diabetes in humans a chronic metabolic disorder characterised by hyperglycaemia, it is associated with an increased risk of cardiovascular disease, disruptions to metabolism and vascular functions. It is also linked to oxidative stress and its complications. Its role in vascular dysfunctions is generally reported without detailed impact on the molecular mechanisms. Potassium ion channel (K+ channels) are key regulators of vascular tone, and as membrane proteins, are modifiable by oxidant stress associated with diabetes. This review manuscript examined the impact of oxidant stress on vascular K+ channel functions in diabetes, its implication in vascular complications and metabolic and cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Loss of function mutations in store‐operated Ca2+ entry (SOCE) are associated with severe paediatric disorders in humans, including combined immunodeficiency, anaemia, thrombocytopenia, anhidrosis and muscle hypotonia. Given its central role in immune cell activation, SOCE has been a therapeutic target for autoimmune and inflammatory diseases. Treatment for such chronic diseases would require prolonged SOCE inhibition. It is, however, unclear whether chronic SOCE inhibition is viable therapeutically. Here we address this issue using a novel genetic mouse model (SOCE hypomorph) with deficient SOCE, nuclear factor of activated T cells activation, and T cell cytokine production. SOCE hypomorph mice develop and reproduce normally and do not display muscle weakness or overt anhidrosis. They do, however, develop cardiovascular complications, including hypertension and tachycardia, which we show are due to increased sympathetic autonomic nervous system activity and not cardiac or vascular smooth muscle autonomous defects. These results assert that chronic SOCE inhibition is viable therapeutically if the cardiovascular complications can be managed effectively clinically. They further establish the SOCE hypomorph line as a genetic model to define the therapeutic window of SOCE inhibition and dissect toxicities associated with chronic SOCE inhibition in a tissue‐specific fashion. Key points: A floxed stromal interaction molecule 1 (STIM1) hypomorph mouse model was generated with significant reduction in Ca2+ influx through store‐operated Ca2+ entry (SOCE), resulting in defective nuclear translocation of nuclear factor of activated T cells, cytokine production and inflammatory response. The hypomorph mice are viable and fertile, with no overt defects.Decreased SOCE in the hypomorph mice is due to poor translocation of the mutant STIM1 to endoplasmic reticulum–plasma membrane contact sites resulting in fewer STIM1 puncta.Hypomorph mice have similar susceptibility to controls to develop diabetes but exhibit tachycardia and hypertension. The hypertension is not due to increased vascular smooth muscle contractility or vascular remodelling.The tachycardia is not due to heart‐specific defects but rather seems to be due to increased circulating catecholamines in the hypomorph.Therefore, long term SOCE inhibition is viable if the cardiovascular defects can be managed clinically. [ABSTRACT FROM AUTHOR]

It is now established that S-nitroso-albumin (SNO-albumin) circulates at low nanomolar concentrations under physiological conditions, but concentrations may increase to micromolar levels during disease states (e.g., cirrhosis or endotoxemia). This study tested the hypothesis that high concentrations of SNO-albumin observed in some diseases modulate vascular function and that it acts as a stable reservoir of nitric oxide (NO), releasing this molecule when the concentrations of low-molecular-weight thiols are increased. SNO-albumin was infused into rats to increase the plasma concentration from S-nitrosothiols; cardiac physiology; N-acetylcysteine

Antidoping testing for recombinant human erythropoietin (EPO) is routinely performed by gel electrophoresis followed by western blot analysis with primary and secondary antibodies. The two antibody steps add more than 24 h to the testing time of a purified sample. The aim of this study was to test the concept of using directly horseradish‐peroxidase (HRP)‐conjugated anti‐EPO primary antibody, without the need for a secondary antibody, to reduce the analysis time and eliminate non‐specific cross‐reactivity with secondary antibodies. An in‐house, periodate coupling (R&D systems, clone AE7A5) and three commercially available anti‐human EPO‐HRP conjugates from Genetex, Novus Biologicals and Santa Cruz were evaluated for specificity and sensitivity, using recombinant human EPO standards, negative human urine samples and urine samples from an EPO excretion study. The in‐house anti‐EPO‐HRP conjugate was performed as well as the current two‐step application of unconjugated primary and secondary antibodies used in routine analysis, with comparable specificity and sensitivity. The analysis time was markedly reduced for purified samples from 25 h with the routine method down to 7 h with the in‐house HRP conjugate. Of the three commercially available conjugates tested, only the Santa Cruz anti‐EPO‐HRP conjugate showed comparable specificity but had lower sensitivity to both the in‐house and the antibody combination currently applied routinely. The other two commercially available conjugates (Genetex and Novus Biologicals) did not show any visible bands with the EPO standards. The results clearly demonstrate the potential utility of a directly HRP‐conjugated anti‐EPO antibody to reduce analysis time for EPO in doping control. [ABSTRACT FROM AUTHOR]

The article focuses on a study which examined the dynamic effects of adenosine triphosphate-sensitive potassium channel pore inhibition in awake, fluid-resuscitated septic rats. The study also investigated the temporal changes in ex-vivo channel activity and subunit gene expression. It concluded that increased adenosine triphosphate-sensitive potassium channel activity is present in sepsis, but is inhibited in vivo by high sympathetic tone.

Abstract: Prostanoid IP receptors coupled to Gs are thought to be the primary target for prostacyclin (PGI2) analogues. However, these agents also activate prostanoid EP1–4 receptor subtypes to varying degrees, which are positively (EP2/4) or negatively (EP3) coupled to adenylate cyclase through Gs or Gi, respectively. We investigated the role of these receptors in modulating relaxation to PGI2 analogues cicaprost, iloprost and treprostinil in pre-contracted segments of rat tail artery. Prostanoid IP (RO1138452), EP4 (GW627368X), EP3 (L-798106), EP1–3 (AH6809), and EP1 (SC-51322) receptor antagonists were used to determine each receptor contribution. The role of Gi/o was investigated using pertussis toxin (PTX), while dependence on cAMP was determined using adenylate cyclase (2′5′dideoxyadenosine, DDA) and protein kinase A (2′-O-monobutyryladenosine- 3′,5′-cyclic monophosphorothioate, Rp- isomer, Rp-2′-O-MB-cAMPS) inhibitors, and by measurement of tissue cAMP. All analogues caused relaxation which was significantly (P <0.01) inhibited by RO1138452; with maximum response to cicaprost, iloprost and treprostinil reduced by 51%, 66% and 37%, respectively. GW627368X had no effect when used alone, but in combination with RO1138452, caused a rightward shift of the curves for cicaprost and iloprost but not treprostinil. PTX treatment potentiated relaxation to all 3 analogues (P< 0.01), as did L798106 and AH6809 but not SC-51322. Basal cAMP levels were higher in PTX-treated tissues and DDA- and Rp-2''-O-MB-cAMPs--sensitive responses increased to analogue concentrations <0.1μM. In conclusion, prostanoid EP3 receptors via Gi/o negatively modulate prostanoid IP receptor-mediated relaxation to cicaprost, iloprost and treprostinil. However, other pathways contribute to analogue-induced vasorelaxation, the nature of which remains unclear for treprostinil. [Copyright &y& Elsevier]

Abstract: Objective: We investigated the role of the inward rectifier potassium (KIR) channel and the cyclic AMP-dependent pathway in mediating vasorelaxation induced by the prostacyclin analogue cicaprost. Methods: Small vessel myography was used to assess responses to cicaprost in segments of rat tail artery contracted with phenylephrine. Microelectrode recordings were made from helical strips to assess effects on membrane potential. Results: Cicaprost caused relaxation and hyperpolarisation that were significantly inhibited by Ba2+ (30–100 μM), a known blocker of KIR channels. Raising extracellular K+ from 5 to 15 mM elicited membrane hyperpolarisation and an endothelium-independent relaxation that was blocked by Ba2+ (30–100 μM), suggesting the existence of functional KIR channels on the smooth muscle. In contrast, neither glibenclamide (10 μM), a blocker of ATP-sensitive K+ channels, nor fluoxetine hydrochloride (100 μM), a blocker of G-protein-gated inward rectifier K+ channels, nor pertussis toxin (PTX; 1 μg/ml), which irreversibly inhibits Gi/Go, reduced relaxation to cicaprost. Indeed, PTX significantly potentiated responses. Relaxation to cicaprost was not mediated by NO but was partially endothelium-dependent, consistent with a similar inhibition by a combination of charybdotoxin (0.1 μM) and apamin (0.5 μM), blockers of endothelium-derived hyperpolarising factor (EDHF). However, relaxation was unaffected by adenylyl cyclase (SQ22536, dideoxyadenosine) or protein kinase A (Rp-2-O-monobutyryl-cAMP) inhibitors, consistent also with Ba2+ only weakly inhibiting relaxation to the adenylyl cyclase activator forskolin. Conclusion: We conclude that cicaprost relaxes rat tail artery by activating KIR channels with some involvement from EDHF. The mechanism appears to be largely independent of cyclic AMP and Gi/Go, although the latter appears to counteract relaxation through an unknown pathway and/or receptor. [Copyright &y& Elsevier]

Diabetes in humans a chronic metabolic disorder characterised by hyperglycaemia, it is associated with an increased risk of cardiovascular disease, disruptions to metabolism and vascular functions. It is also linked to oxidative stress and its complications. Its role in vascular dysfunctions is generally reported without detailed impact on the molecular mechanisms. Potassium ion channel (K + channels) are key regulators of vascular tone, and as membrane proteins, are modifiable by oxidant stress associated with diabetes. This review manuscript examined the impact of oxidant stress on vascular K + channel functions in diabetes, its implication in vascular complications and metabolic and cardiovascular diseases.

Loss of function mutations in store-operated Ca 2+ entry (SOCE) are associated with severe paediatric disorders in humans, including combined immunodeficiency, anaemia, thrombocytopenia, anhidrosis and muscle hypotonia. Given its central role in immune cell activation, SOCE has been a therapeutic target for autoimmune and inflammatory diseases. Treatment for such chronic diseases would require prolonged SOCE inhibition. It is, however, unclear whether chronic SOCE inhibition is viable therapeutically. Here we address this issue using a novel genetic mouse model (SOCE hypomorph) with deficient SOCE, nuclear factor of activated T cells activation, and T cell cytokine production. SOCE hypomorph mice develop and reproduce normally and do not display muscle weakness or overt anhidrosis. They do, however, develop cardiovascular complications, including hypertension and tachycardia, which we show are due to increased sympathetic autonomic nervous system activity and not cardiac or vascular smooth muscle autonomous defects. These results assert that chronic SOCE inhibition is viable therapeutically if the cardiovascular complications can be managed effectively clinically. They further establish the SOCE hypomorph line as a genetic model to define the therapeutic window of SOCE inhibition and dissect toxicities associated with chronic SOCE inhibition in a tissue-specific fashion. KEY POINTS: A floxed stromal interaction molecule 1 (STIM1) hypomorph mouse model was generated with significant reduction in Ca 2+ influx through store-operated Ca 2+ entry (SOCE), resulting in defective nuclear translocation of nuclear factor of activated T cells, cytokine production and inflammatory response. The hypomorph mice are viable and fertile, with no overt defects. Decreased SOCE in the hypomorph mice is due to poor translocation of the mutant STIM1 to endoplasmic reticulum-plasma membrane contact sites resulting in fewer STIM1 puncta. Hypomorph mice have similar susceptibility to controls to develop diabetes but exhibit tachycardia and hypertension. The hypertension is not due to increased vascular smooth muscle contractility or vascular remodelling. The tachycardia is not due to heart-specific defects but rather seems to be due to increased circulating catecholamines in the hypomorph. Therefore, long term SOCE inhibition is viable if the cardiovascular defects can be managed clinically., (© 2022 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

Objective: We investigated the role of the inward rectifier potassium (KIR) channel and the cyclic AMP-dependent pathway in mediating vasorelaxation induced by the prostacyclin analogue cicaprost., Methods: Small vessel myography was used to assess responses to cicaprost in segments of rat tail artery contracted with phenylephrine. Microelectrode recordings were made from helical strips to assess effects on membrane potential., Results: Cicaprost caused relaxation and hyperpolarisation that were significantly inhibited by Ba2+ (30-100 microM), a known blocker of KIR channels. Raising extracellular K+ from 5 to 15 mM elicited membrane hyperpolarisation and an endothelium-independent relaxation that was blocked by Ba2+ (30-100 microM), suggesting the existence of functional KIR channels on the smooth muscle. In contrast, neither glibenclamide (10 microM), a blocker of ATP-sensitive K+ channels, nor fluoxetine hydrochloride (100 microM), a blocker of G-protein-gated inward rectifier K+ channels, nor pertussis toxin (PTX; 1 microg/ml), which irreversibly inhibits Gi/Go, reduced relaxation to cicaprost. Indeed, PTX significantly potentiated responses. Relaxation to cicaprost was not mediated by NO but was partially endothelium-dependent, consistent with a similar inhibition by a combination of charybdotoxin (0.1 microM) and apamin (0.5 microM), blockers of endothelium-derived hyperpolarising factor (EDHF). However, relaxation was unaffected by adenylyl cyclase (SQ22536, dideoxyadenosine) or protein kinase A (Rp-2-O-monobutyryl-cAMP) inhibitors, consistent also with Ba2+ only weakly inhibiting relaxation to the adenylyl cyclase activator forskolin., Conclusion: We conclude that cicaprost relaxes rat tail artery by activating KIR channels with some involvement from EDHF. The mechanism appears to be largely independent of cyclic AMP and Gi/Go, although the latter appears to counteract relaxation through an unknown pathway and/or receptor.