Crucial role for sensory nerves and Na/H exchanger inhibition in dapagliflozin- and empagliflozin-induced arterial relaxation.

Aims: Sodium/glucose transporter 2 (SGLT2 or SLC5A2) inhibitors lower blood glucose and are also approved treatments for heart failure independent of raised glucose. Various studies have showed that SGLT2 inhibitors relax arteries, but the underlying mechanisms are poorly understood and responses variable across arterial beds. We speculated that SGLT2 inhibitor-mediated arterial relaxation is dependent upon calcitonin gene-related peptide (CGRP) released from sensory nerves independent of glucose transport.

Stimulation of the calcium-sensing receptor induces relaxations through CGRP and NK1 receptor-mediated pathways in male rat mesenteric arteries.

Stimulation of the calcium-sensing receptor (CaSR) regulates vascular contractility, but cellular mechanisms involved remain unclear. This study investigated the role of perivascular sensory nerves in CaSR-induced relaxations of male rat mesenteric arteries. In fluorescence studies, colocalisation between synaptophysin, a synaptic vesicle marker, and the CaSR was present in the adventitial layer of arterial segments.

G protein βγ regulation of KCNQ-encoded voltage-dependent K channels.

The KCNQ family is comprised of five genes and the expression products form voltage-gated potassium channels (Kv7.1-7.5) that have a major impact upon cellular physiology in many cell types.

Stimulation of the calcium-sensing receptor induces relaxations of rat mesenteric arteries by endothelium-dependent and -independent pathways via BK and K channels.

Stimulation of the calcium-sensing receptor (CaSR) induces both vasoconstrictions and vasorelaxations but underlying cellular processes remain unclear. This study investigates expression and effect of stimulating the CaSR by increasing external Ca concentration ([Ca ] ) on contractility of rat mesenteric arteries. Immunofluorescence studies showed expression of the CaSR in perivascular nerves, vascular smooth muscle cells (VSMCs), and vascular endothelium cells.

Crucial role for Sodium Hydrogen Exchangers in SGLT2 inhibitor-induced arterial relaxations.

Introduction: Sodium dependent glucose transporter 2 (SGLT2 or SLC5A2) inhibitors effectively lower blood glucose and are also approved treatments for heart failure independent of raised glucose. One component of the cardioprotective effect is reduced cardiac afterload but the mechanisms underlying peripheral relaxation are ill defined and variable. We speculated that SGLT2 inhibitors promoted arterial relaxation via the release of the potent vasodilator calcitonin gene-related peptide (CGRP) from sensory nerves independent of glucose transport.

ANO1, CaV1.2, and IP3R form a localized unit of EC-coupling in mouse pulmonary arterial smooth muscle.

Pulmonary arterial (PA) smooth muscle cells (PASMC) generate vascular tone in response to agonists coupled to Gq-protein receptor signaling. Such agonists stimulate oscillating calcium waves, the frequency of which drives the strength of contraction. These Ca2+ events are modulated by a variety of ion channels including voltage-gated calcium channels (CaV1.

The novel K7 channel activator URO-K10 exerts enhanced pulmonary vascular effects independent of the KCNE4 regulatory subunit.

K7 channels exert a pivotal role regulating vascular tone in several vascular beds. In this context, K7 channel agonists represent an attractive strategy for the treatment of pulmonary arterial hypertension (PAH). Therefore, in this study, we have explored the pulmonary vascular effects of the novel K7 channel agonist URO-K10.

Cycling matters: Sex hormone regulation of vascular potassium channels.

Sex hormones and the reproductive cycle (estrus in rodents and menstrual in humans) have a known impact on arterial function. In spite of this, sex hormones and the estrus/menstrual cycle are often neglected experimental factors in vascular basic preclinical scientific research. Recent research by our own laboratory indicates that cyclical changes in serum concentrations of sex -hormones across the rat estrus cycle, primary estradiol, have significant consequences for the subcellular trafficking and function of K.

Key role for Kv11.1 (ether-a-go-go related gene) channels in rat bladder contractility.

In addition, to their established role in cardiac myocytes and neurons, ion channels encoded by ether-a-go-go-related genes (ERG1-3 or kcnh2,3 and 6) (kcnh2) are functionally relevant in phasic smooth muscle. The aim of the study was to determine the expression and functional impact of ERG expression products in rat urinary bladder smooth muscle using quantitative polymerase chain reaction, immunocytochemistry, whole-cell patch-clamp and isometric tension recording. kcnh2 was expressed in rat bladder, whereas kcnh6 and kcnh3 expression were negligible.

Marked oestrous cycle-dependent regulation of rat arterial K 7.4 channels driven by GPER1.

Background And Purpose: Kcnq-encoded K 7 channels (termed K 7.1-5) regulate vascular smooth muscle cell (VSMC) contractility at rest and as targets of receptor-mediated responses. However, the current data are mostly derived from males.

Sexual dimorphism in prostacyclin-mimetic responses within rat mesenteric arteries: A novel role for K 7.1 in shaping IP receptor-mediated relaxation.

Background And Purpose: Prostacyclin mimetics express potent vasoactive effects via prostanoid receptors that are not unequivocally defined, as to date no study has considered sex as a factor. The aim of this study was to determine the contribution of IP and EP prostanoid receptors to prostacyclin mimetic iloprost-mediated responses, whether K 7.1-5 channels represent downstream targets of selective prostacyclin-IP-receptor agonist MRE-269 and the impact of the oestrus cycle on vascular reactivity.

A small molecule inhibitor of the chloride channel TMEM16A blocks vascular smooth muscle contraction and lowers blood pressure in spontaneously hypertensive rats.

Hypertension is a major cause of cardiovascular morbidity and mortality, despite the availability of antihypertensive drugs with different targets and mechanisms of action. Here, we provide evidence that pharmacological inhibition of TMEM16A (ANO1), a calcium-activated chloride channel expressed in vascular smooth muscle cells, blocks calcium-activated chloride currents and contraction in vascular smooth muscle in vitro and decreases blood pressure in spontaneously hypertensive rats. The acylaminocycloalkylthiophene TMinh-23 fully inhibited calcium-activated TMEM16A chloride current with nanomolar potency in Fischer rat thyroid cells expressing TMEM16A, and in primary cultures of rat vascular smooth muscle cells.

Dynein regulates Kv7.4 channel trafficking from the cell membrane.

The dynein motor protein transports proteins away from the cell membrane along the microtubule network. Recently, we found the microtubule network was important for regulating the membrane abundance of voltage-gated Kv7.4 potassium channels in vascular smooth muscle.

K7 Channel Expression and Function Within Rat Mesenteric Endothelial Cells.

Arterial diameter is dictated by the contractile state of the vascular smooth muscle cells (VSMCs), which is modulated by direct and indirect inputs from endothelial cells (ECs). Modulators of KCNQ-encoded k7 channels have considerable impact on arterial diameter and these channels are known to be expressed in VSMCs but not yet defined in ECs. However, expression of k7 channels in ECs would add an extra level of vascular control.

Uncovered Contribution of Kv7 Channels to Pulmonary Vascular Tone in Pulmonary Arterial Hypertension.

K channels play a fundamental role regulating membrane potential of pulmonary artery (PA) smooth muscle cells and their impairment is a common feature in pulmonary arterial hypertension (PAH). K voltage-gated channel subfamily Q () or Kv7 channels and their regulatory subunits subfamily E (KCNE) regulatory subunits are known to regulate vascular tone, but whether Kv7 channel function is impaired in PAH and how this can affect the rationale for targeting Kv7 channels in PAH remains unknown. Here, we have studied the role of Kv7/KCNE subunits in rat PA and their possible alteration in PAH.

SMIT (Sodium-Myo-Inositol Transporter) 1 Regulates Arterial Contractility Through the Modulation of Vascular Kv7 Channels.

Objective: The SMIT1 (sodium:myo-inositol transporter 1) regulates myo-inositol movement into cells and responses to hypertonic stimuli. Alteration of myo-inositol levels has been associated with several diseases, including hypertension, but there is no evidence of a functional role of SMIT1 in the vasculature. Recent evidence showed that in the nervous system SMIT1 interacted and modulated the function of members of the Kv7 family of voltage-gated potassium channels, which are also expressed in the vasculature where they regulate arterial contractility.

MARCKS mediates vascular contractility through regulating interactions between voltage-gated Ca channels and PIP.

Phosphatidylinositol 4,5-bisphosphate (PIP) acts as substrate and unmodified ligand for Gq-protein-coupled receptor signalling in vascular smooth muscle cells (VSMCs) that is central for initiating contractility. The present work investigated how PIP might perform these two potentially conflicting roles by studying the effect of myristoylated alanine-rich C kinase substrate (MARCKS), a PIP-binding protein, on vascular contractility in rat and mouse mesenteric arteries. Using wire myography, MANS peptide (MANS), a MARCKS inhibitor, produced robust contractions with a pharmacological profile suggesting a predominantly role for L-type (CaV1.

Cyclic AMP-Dependent Regulation of Kv7 Voltage-Gated Potassium Channels.

Voltage-gated Kv7 potassium channels, encoded by genes, have major physiological impacts cardiac myocytes, neurons, epithelial cells, and smooth muscle cells. Cyclic adenosine monophosphate (cAMP), a well-known intracellular secondary messenger, can activate numerous downstream effector proteins, generating downstream signaling pathways that regulate many functions in cells. A role for cAMP in ion channel regulation has been established, and recent findings show that cAMP signaling plays a role in Kv7 channel regulation.

The Gβ1 and Gβ3 Subunits Differentially Regulate Rat Vascular Kv7 Channels.

Within the vasculature Kv7 channels are key regulators of basal tone and contribute to a variety of receptor mediated vasorelaxants. The Kv7.4 isoform, abundant within the vasculature, is key to these processes and was recently shown to have an obligatory requirement of G-protein βγ subunits for its voltage dependent activity.

Molecular mechanism of TMEM16A regulation: role of CaMKII and PP1/PP2A.

This study explored the mechanism by which Ca-activated Cl channels (CaCCs) encoded by the gene are regulated by calmodulin-dependent protein kinase II (CaMKII) and protein phosphatases 1 (PP1) and 2A (PP2A). Ca-activated Cl currents () were recorded from HEK-293 cells expressing mouse TMEM16A. were evoked using a pipette solution in which free Ca concentration was clamped to 500 nM, in the presence (5 mM) or absence of ATP.

TMEM16A is implicated in the regulation of coronary flow and is altered in hypertension.

Background And Purpose: Coronary artery disease leads to ischaemic heart disease and ultimately myocardial infarction. Thus, it is important to determine the factors that regulate coronary blood flow. Ca -activated chloride channels contribute to the regulation of arterial tone; however, their role in coronary arteries is unknown.

Interaction Between Pannexin 1 and Caveolin-1 in Smooth Muscle Can Regulate Blood Pressure.

Objective- Sympathetic nerve innervation of vascular smooth muscle cells (VSMCs) is a major regulator of arteriolar vasoconstriction, vascular resistance, and blood pressure. Importantly, α-adrenergic receptor stimulation, which uniquely couples with Panx1 (pannexin 1) channel-mediated ATP release in resistance arteries, also requires localization to membrane caveolae. Here, we test whether localization of Panx1 to Cav1 (caveolin-1) promotes channel function (stimulus-dependent ATP release and adrenergic vasoconstriction) and is important for blood pressure homeostasis.

Investigating the Role of G Protein βγ in Kv7-Dependent Relaxations of the Rat Vasculature.

Objective- In renal arteries, inhibitors of G protein βγ subunits (Gβγ) reduce Kv7 activity and inhibit Kv7-dependent receptor-mediated vasorelaxations. However, the mechanisms underlying receptor-mediated relaxation are artery specific. Consequently, the aim of this study was to ascertain the role of Gβγ in Kv7-dependent vasorelaxations of the rat vasculature.

Angiotensin II Promotes K7.4 Channels Degradation Through Reduced Interaction With HSP90 (Heat Shock Protein 90).

Voltage-gated K7.4 channels have been implicated in vascular smooth muscle cells' activity because they modulate basal arterial contractility, mediate responses to endogenous vasorelaxants, and are downregulated in several arterial beds in different models of hypertension. Angiotensin II (Ang II) is a key player in hypertension that affects the expression of several classes of ion channels.