HCN2 receptor - "Biophysical modulation of hHCN2 by bPAC recorded on the SyncroPatch 384PE"
SyncroPatch 384PE (a predecessor model of SyncroPatch 384i) application note: (1.0 MB)
Cells were engineered and kindly provided by Axxam S.p.A.
Neuronal and cardiac rhythmicity is predominantly controlled by hyperpolarization activated cyclic nucleotide gated (HCN) channels. The HCN family comprises four members (HCN1-4) which are ubiquitously expressed in the central and peripheral nervous system. Activated by hyperpolarization, HCN channels open slowly with no inactivation. Cyclic AMP (and other second messenger proteins) affects the activation properties independent of phosphorylation, modulating the voltage dependence of current activation and accelerating the kinetics of channel opening. HCN mediates a Na+/K+ conductance (Ih) which contributes to the establishment of the resting membrane potential. It is therefore not surprising that HCN channels play an important role in the regulation of neuronal firing and excitability as well as pacemaking. Disruption of HCN function slows down the heart rate and provides a potential target for the treatment of neuronal disorders such as epilepsy and neuropathic pain.
Here we present data collected on the SyncroPatch 384PE showing pharmacology and modulation of hHCN2 expressed in HEK cells. In addition, these cells heterologously express a light-sensitive bacterial phospho-adelynate cyclase (bPAC). We demonstrate two ways of triggering the cAMP pathway in order to modulate the HCN2 channel opening kinetics. First, we used the internal perfusion system of the SyncroPatch 384PE for direct application of cAMP to the intracellular environment. Second, we triggered the cAMP pathway by optical stimulation of bPAC. Further, we showed voltage dependent block of Ih with Cs+ and ZD7288. Ivabradine, a drug used for symptomatic management of stable heart related chest pain and heart failure blocked the channel with an IC50 of 0.1 mM in good agreement the literature.