TRPC3 properties of a native constitutively active Ca²⁺‐permeable cation channel in rabbit ear artery myocytes

Abstract

Previously we have described a constitutively active, Ca2+ -permeable, non-selective cation channel in freshly dispersed rabbit ear artery myocytes which has similar properties to some of the canonical transient receptor potential (TRPC) channel proteins. In the present work we have compared the properties of constitutive channel activity with known properties of TRPC proteins by investigating the effect of selective anti-TRPC antibodies and pharmacological agents on whole-cell and single cation channel activity. Bath application of anti-TRPC3 antibodies markedly reduced channel activity in inside-out patches and also produced a pronounced reduction of both current amplitude and variance of constitutively active whole-cell cation currents whereas anti-TRPC1/4/5/6/7 antibodies had no effect on channel activity. In the presence of antigenic peptide, anti-TRPC3 antibodies had no effect on whole-cell or single cation channel activity. Bath application of flufenamic acid, Gd 3+ , La 3+ and Ca 2+ inhibited spontaneous channel activity in outside-out patches with IC 50 values of 6.8 μM, 25 nM, 1.5 μM and 0.124 mM, respectively, which are similar values to those against TRPC3 proteins. Immunocytochemical studies combined with confocal microscopy showed expression of TRPC3 proteins in ear artery myocytes, and these were predominately distributed at, or close to, the plasma membrane. These data provide strong evidence that native constitutively active cation channels in rabbit ear artery myocytes have similar properties to TRPC3 channel proteins and indicate that these proteins may have an important role in mediating this conductance.

Lack of Kinase Regulation of Canonical Transient Receptor Potential 3 (TRPC3) Channel-dependent Currents in Cerebellar Purkinje Cells

“…Furthermore, the rat mGluR1-mediated slow EPSC was significantly inhibited by inclusion of an inhibitory TRPC3 antibody (Fig. 1D) that was shown to inhibit native TRPC3 channels in rabbit artery myocytes (30). All these lines of evidence strongly suggest crucial involvement of TRPC3 in rat cerebellar slow EPSC.…”

ACh-induced depolarization in inner ear artery is generated by activation of a TRP-like non-selective cation conductance and inactivation of a potassium conductance

“…It has been shown that the whole-cell current of TRPC6, not the TRPC3 or TRPC7, channels exhibited a U-shaped I/V relation, being similar to that of the ACh-current we observed (Fig. 5C, Albert et al, 2003;Albert et al, 2006b;Jung et al, 2002;Peppiatt-Wildman et al, 2007;Shi et al, 2004). In this regard, it is possible that TRPC6 may participate in the formation of a heteromeric NSCC channel that mediates the ACh-depolarization or inward current.…”

“…Among the TRP members expressed in blood vessels, four of the seven TRPC subfamily members (TRPC1, 3, 6 and 7) form NSCC channels that are blocked by La 3+ while TRPC4 and TRPC5 channels are activated by 100 μM La 3+ (Albert et al, 2006b;Clapham, 2007). FFA blocks the cation currents mediated by TRPC3, 5, 7, TRPM4 and TRPP2 (Albert et al, 2006b;Clapham, 2007;Peppiatt-Wildman et al, 2007), but it potentiates the cation currents mediated by TRPC1 and TRPC6 (Hill et al, 2006;Inoue et al, 2001;Jung et al, 2002;Saleh et al, 2006). Since the ACh-depolarization presently studied was inhibited by both La 3+ and FFA, involvement of homomeric channels of TRPC1, TRPC4, TRPC5 and TRPC6 seems unlikely.…”

Transient Receptor Potential Canonical Channels Regulate the Induction of Cerebellar Long-Term Depression

“…To selectively block a certain type of TRPC channel in cerebellar LTD induction, Purkinje cells were loaded with specific antibodies directed against a cytoplasmic epitope of TRPC3 in the internal solution (0.5 g/ml) (Alomone Labs) (Albert et al, 2006;Alvarez et al, 2008). TRPC3 was selected among various subtypes of the TRPC family since the sEPSC in Purkinje cells is absent in TRPC3 knock-out mice (Hartmann et al, 2008).…”