Resting Membrane Potential Case Study

1. The resting membrane potential is the potential difference across the cell membrane of excitable cells such as nerve and muscle cells. The 3 major factors that establish a resting membrane potential are as follows:
(1) Non-diffusible anions: The resting membrane potential is influenced by the presence of large non-diffusible anions (proteins, nucleic acids and organic phosphates) inside a cell. The presence of large non-diffusible anions inside a cell attracts a large number of cations and repeals anions. This alteration in the distribution of permeable ions across the membrane establishes the Gibbs-Donnan equilibrium, which creates a potential difference across a cell membrane.
(2) Sodium/Potassium ATPase pumps: Sodium/Potassium ATPase pump is a transporter that uses ATP to transport Sodium (Na+) and Potassium (K+) against their concentration gradient across the cell membrane. Na+/K+ pump creates an electrochemical gradient across the cell membrane by pumping 3 Na+ out of the cell and 2 K+ into the cell. The greater outflow of positive sodium ion makes the cytoplasm more negative, which help establish a resting …show more content…
The dihydropyridine receptor (DHPR) is a voltage-gated Ca++ channel located in the T-tubule membrane. DHPR plays a role in excitation-contraction coupling in both skeletal and cardiac muscle, it specifically facilitates the release of Ca++ during muscle contraction. Even though DHPR is present in both skeletal and cardiac muscle, it functions differently in the two muscle types. DHPR in skeletal muscle is physically connected to the ryanodine receptor (RyR), thus, Ca++ release in skeletal muscle is due to the conformational change in DHRP (electromechanical coupling). However, DHPR in cardiac muscle is not physically connected to the RyR, therefore cardiac muscle undergoes Ca++ induced Ca++ release (electrochemical coupling). Regardless of this difference in Ca++ release, DHPR in both skeletal and cardiac muscle plays a role in muscle