Regulation of P2X1 receptors by modulators of the cAMP effectors PKA and EPAC.

P2X1 receptors are adenosine triphosphate (ATP)-gated cation channels that are functionally important for male fertility, bladder contraction, and platelet aggregation. The activity of P2X1 receptors is modulated by lipids and intracellular messengers such as cAMP, which can stimulate protein kinase A (PKA). Exchange protein activated by cAMP (EPAC) is another cAMP effector; however, its effect on P2X1 receptors has not yet been determined.

LINGO1 is a regulatory subunit of large conductance, Ca-activated potassium channels.

LINGO1 is a transmembrane protein that is up-regulated in the cerebellum of patients with Parkinson's disease (PD) and Essential Tremor (ET). Patients with additional copies of the LINGO1 gene also present with tremor. Pharmacological or genetic ablation of large conductance Ca-activated K (BK) channels also result in tremor and motor disorders.

Inhibitory effects of openers of large-conductance Ca-activated K channels on agonist-induced phasic contractions in rabbit and mouse bronchial smooth muscle.

Airway smooth muscle expresses abundant BK channels, but their role in regulating contractions remains controversial. This study examines the effects of two potent BK channel openers on agonist-induced phasic contractions in rabbit and mouse bronchi. First, we demonstrated the ability of 10 μM GoSlo-SR5-130 to activate BK channels in inside-out patches from rabbit bronchial myocytes, where it shifted the activation V by -88 ± 11 mV (100 nM Ca, n = 7).

The role of Ca-activated Cl current in tone generation in the rabbit corpus cavernosum.

Rabbit corpus cavernosum smooth muscle (RCCSM) cells express ion channels that produce Ca-activated Cl () current, but low sensitivity to conventional antagonists has made its role in tone generation difficult to evaluate. We have reexamined this question using two new generation blockers, T16A-A01 and CaCC-A01. Isolated RCCSM cells were studied using the perforated patch method.

Effects of new-generation TMEM16A inhibitors on calcium-activated chloride currents in rabbit urethral interstitial cells of Cajal.

Interstitial cells of Cajal (ICC) isolated from the rabbit urethra exhibit Ca-activated Cl currents (I ) that are important for the development of urethral tone. Here, we examined if TMEM16A (ANO1) contributed to this activity by examining the effect of "new-generation" TMEM16A inhibitors, CACC-A01 and T16A-A01, on I recorded from freshly isolated rabbit urethral ICC (RUICC) and on contractions of intact strips of rabbit urethra smooth muscle. Real-time quantitative PCR experiments demonstrated that TMEM16A was highly expressed in rabbit urethra smooth muscle, in comparison to TMEM16B and TMEM16F.

Differential efficacy of GoSlo-SR compounds on BKα and BKαγ channels.

Large conductance, voltage and Ca activated K channels (BK channels) are abundantly expressed throughout the body and are important regulators of smooth muscle tone and neuronal excitability. Their dysfunction is implicated in various diseases including overactive bladder, hypertension and erectile dysfunction. Therefore, BK channel openers bear significant therapeutic potential to treat the above diseases.

The role of Ca(2+) influx in spontaneous Ca(2+) wave propagation in interstitial cells of Cajal from the rabbit urethra.

Tonic contractions of rabbit urethra are associated with spontaneous electrical slow waves that are thought to originate in pacemaker cells termed interstitial cells of Cajal (ICC). ICC pacemaker activity results from their ability to generate propagating Ca(2+) waves, although the exact mechanisms of propagation are not understood. In this study, we have identified spontaneous localised Ca(2+) events for the first time in urethral ICC; these were due to Ca(2+) release from the endoplasmic reticulum (ER) via ryanodine receptors (RyRs) and, while they often remained localised, they sometimes initiated propagating Ca(2+) waves.

Molecular mechanisms underlying the effect of the novel BK channel opener GoSlo: involvement of the S4/S5 linker and the S6 segment.

GoSlo-SR-5-6 is a novel large-conductance Ca(2+)-activated K(+) (BK) channel agonist that shifts the activation V1/2 of these channels in excess of -100 mV when applied at a concentration of 10 μM. Although the structure-activity relationship of this family of molecules has been established, little is known about how they open BK channels. To help address this, we used a combination of electrophysiology, mutagenesis, and mathematical modeling to investigate the molecular mechanisms underlying the effect of GoSlo-SR-5-6.

Development of GoSlo-SR-5-69, a potent activator of large conductance Ca2+-activated K+ (BK) channels.

We have designed, synthesised and characterised the effects of a number of novel anthraquinone derivatives and assessed their effects on large conductance, Ca(2+) activated K(+) (BK) channels recorded from rabbit bladder smooth muscle cells using the excised, inside/out configuration of the patch clamp technique. These compounds are members of the GoSlo-SR family of compounds, which potently open BK channels and shift the voltage required for half maximal activation (V1/2) negatively. The efficacy of the anilinoanthraquinone derivatives was enhanced when the size of ring D was increased, since the cyclopentane and cyclohexane derivatives shifted the V1/2, by -24 ± 6 mV and -54 ± 8 mV, respectively, whereas the cycloheptane and cyclooctane derivatives shifted the V1/2 by -61 ± 6 mV and -106 ± 6 mV.

Structure-activity relationships of a novel group of large-conductance Ca(2+)-activated K(+) (BK) channel modulators: the GoSlo-SR family.

Opening up ion channels: We synthesised a series of anthraquinone analogues, called the GoSlo-SR family. Their effects on bladder smooth muscle BK channels were examined and, as shown, shifted voltage dependent activation >-100 mV (at 10 μM). They were more efficacious than NS11021 and could provide a new scaffold for the design of efficacious BK openers.

Microarray comparison of normal and W/Wv mice in the gastric fundus indicates a supersensitive phenotype.

Interstitial cells of Cajal (ICC) have been identified in specific areas throughout the smooth musculature of the gastrointestinal (GI) tract. Located within the circular and longitudinal muscle layers of the gastric fundus lies a specific type of ICC, termed "intramuscular" ICC or IC-IM. The principal function of this cell type is to act as "mediators of excitatory and inhibitory enteric neurotransmission.