As shown in Discussion LPLUNC1 is located on chromosome 20 and belongs to the PLUNC family

ly recovering transient outward K+ current IKto,f obtained by Zhang et al. from mouse Schwann cells after application of 1 mM forskolin or 10 mM db-cAMP, and corresponding simulated time course of a relative decrease in IKto,f phosphorylation obtained with our model after stimulation with 10 mM isoproterenol. Panel E: Simulated time course of IKto,f traces obtained by depolarization pulses to 25 mV from a holding potential of 2100 mV for control and after stimulation with 10 mM isoproterenol. Panel F: Simulated data for G/Gmax and steady-state inactivation relationships obtained for IKto,f with two-pulse protocol in control and after application of 10 mM isoproterenol. doi:10.1371/journal.pone.0089113.g013 running the model equations without electrical stimulations until changes in each variable did not exceed 0.01%. To generate action potentials, a stimulus current, Istim, was applied with the frequencies from 1 to 5 Hz. Voltage-clamp protocols for ionic currents are described in corresponding figure legends. Results In this paper, our model for action potential and Ca2+ dynamics in an apical mouse cardiac cell was extended to include a b1-adrenergic signaling system by using, in considerable part, the methodology from the previously published models. Unlike models, our model represents a compartmentalized b1-adrenergic signaling system. While the model of Hejiman et al. also includes a compartmentalized b1-adrenergic signaling system, it is developed for larger species and is verified with a different set of experimental data. In particular, our model differs from the Hejiman et al. model in the following: 1) our model was verified in significant part by the experimental data from mice; 2) the model was developed for a different species and includes a significantly different set of ionic currents; 3) TMS PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19640586 the model considers non-zero phosphorylation levels of the protein kinase A substrates before activation of the b1-adrenergic signaling system; 4) the model includes additional modulation of adenylyl cyclases by bc-subunits of stimulatory G-protein, Gs; 5) the model data is compared in significant part with both absolute and relative magnitudes of the activities of major signaling molecules of the b1-adrenergic signaling system; 6) the model includes two subpopulations of the L-type Ca2+ channels located both in the caveolae and extracaveolae compartments; 7) ryanodine receptors are localized in the extracaveolae compartment. Our model also differs from PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19639654 the recently published Yang and Saucerman model for mouse ventricular myocytes in the following: 1) compartmentalization of b1-adrenergic signaling system; 2) inclusion of different types of adenylyl cyclases and phosphodiesterases, their compartmentalization and specific regulation by drugs; 3) multicompartmental distribution of protein kinase A targets and the possibility of their separate regulation by drugs; 4) the effects of b1aderenergic signaling system not only on Ca2+ dynamics, but also on action potential. cAMP Dynamics During Activation of b1-adrenergic Signaling System: the Effects of Phosphodiesterases First, we investigated the behavior of cAMP and PKA catalytic subunit concentrations in different cellular compartments in response to the activation of the b1-adrenergic signaling system Adrenergic Signaling in Mouse Myocytes cAMP fluxes between the subcellular compartments contribute to cAMP transients. At early times, up to,30 s, the largest flux is from the caveolae to the c