30mV Which transporter would you target for the following, and how? Sinoatrial n

Question

30mV Which transporter would you target for the following, and how? Sinoatrial node Atrial Ventricular Phase 2 Phase 4 Increase HR Na -Decrease HR CaT Ca - Increase force Decrease forceof Ito.s Kur Ks K1 KATP kAch FIGURE 1| Schematic cardiac action potentials from different regions of the heart, with the currents that generate them. Colored lines indicate the phase of the action potential that the current participates in. Inward currents are in red, outward currents in blue. Currents-l Na, inward Na +CaT, T-type Ca 2+ CaL, L-type Ca 2+; I to,f, fast transient outward; I to,s, slow transient outward, I Kur, ultra-rapid Kdelayed rectifier; I Ks, slow K+ delayed rectifier, I Kr, rapid K+ delayed rectifier; I K1, inward rectifier, I , ADP-activated K + channel; I KACh , muscarinic-gated K + channel: I f , "funny" current; I NCX , Na + /Ca 2+ exchange current.

Explanation / Answer

For heart rate related things the pacemaker cells or the sino atrial node channels are involved. Mainly inward current causes depolarisation so I CaT , I CaL , If, INCK . response is an increase in intracellular cyclic AMP (cAMP) that raises the rate of action potential generation in the heart pacemhyperpolarization-activated cyclic nucleotide–gated (HCN) channels are the main regulator of the heart rate, and groups promoting a model in which intracellular Ca2+ oscillations affecting currents through Na+/Ca2+ exchangers are the main regulator of the heart rateaker, the sinoatrial (SA) node . The increased firing rate in the SA node increases the heart rate and cardiac output necessary to deliver more oxygen and nutrients to the muscles for the flight-or-fight response. cAMP-activated protein kinases (PKA) have been shown to phosphorylate ryanodine receptors and other Ca2+-cycling proteins in the SA node, leading to altered calcium cycles and increased diastolic currents through Na+/Ca2+ exchangers.

And similarly in contrast the SA Nodal channels are also involved to decrease heart rate mainly Iks and Ikr.

To increase or decrease force of contraction the main channels are of calcium and potassium mainly.

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