Indirect coupling between Ca_v1.2 channels and ryanodine receptors to generate Ca²⁺ sparks in murine arterial smooth muscle cells

Abstract

In arterial vascular smooth muscle cells (VSMCs),

Local control of TRPV4 channels by AKAP150-targeted PKC in arterial smooth muscle

“…The analysis described here also sheds light on why TRPV4 channels, but not Ca V 1.2 channels, can activate RyRs located in the junctional SR of arterial myocytes (Earley et al, 2005(Earley et al, , 2009Essin et al, 2007;Takeda et al, 2011). In principle, the coupling strength between RyRs and TRPV4 or Ca V 1.2 channels is determined by multiple factors including their proximity, the amplitude of the local [Ca 2+ ] i signal produced by sparklets, and the sensitivity of RyRs to Ca 2+ .…”

High K+-induced contraction requires depolarization-induced Ca2+ release from internal stores in rat gut smooth muscle

“…Thus, it is at least conceivable that in gut smooth muscle cells Ca v 1.1 may also be functionally present. However, the direct coupling between RyR1 and the predominant smooth muscle VGCC subtype Ca v 1.2 is still under debate [37] . Our data support the existence of a coupling mechanism between smooth muscle L-type VGCCs and ryanodine receptors beyond CICR.…”

Calcium Cycling in Synthetic and Contractile Phasic or Tonic Vascular Smooth Muscle Cells

“…Some of the entry mechanisms characterized include the Na +/ Ca 2+ exchanger (NCX) operating in its reverse mode [32,44,49], the ATP-sensitive P2X receptor responsible for generating junctional Ca 2+ transients (jCaTs) [50] or the L-type Cav1.2 channels operating as clusters in a "high open probability mode" to produce persistent Ca 2+ sparklets [51]. In the case of the latter, entry of Ca 2+ through these L-type channel clusters does not directly activate RyR to produce sparks, but provides the necessary amount of Ca 2+ to charge up the ER and sensitize the RyR [52]. Another way of internal store reloading is achieved by the various isoforms of the transient receptor potential (TRP) ion channel family, activated directly by DAG [5,6].…”