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Smooth Muscle SG

Smooth Muscle

Name the 2 major extremes of smooth muscle Unitary (same as visceral) and multiunit. In unitary the cells are very close together and contract in an extremely coordinated manner.
EDRF Enoothelium derived relaxing factor very much in the region where neurotransmitters are released
Does smM have the ability to down regulate its energy? Yes. So it can maintain high levels of force w/o using too much energy. It can generate a lot of force even with anaerobic oxidation
What are the dense bodies attachment for? Thin filaments
What are the thick filaments used for? Actin, myosin interaction. Sliding filament mechanism
Name thin filament associated proteins Actin, Tropomyosin, Caldesmin, Calponin and Calmodulin
Name thick filament associated proteins Myosin heavy and light chain and MLCK
What is equivalent to Troponin I and C in smM? Caldesmin and Calponin= Troponin I and Calmodulin= Troponin C
What phosphorylates the Myosin light chains? MLC kinase. This causes increase in force and ATP consumption/ ATPase activity caused by the myosin-actin interaction to generate force. Kinase is stimulated by calcium-calmodulin
What phosphorylates MLCK? PKA and this leads to decrease in calcium action
MLC phosphatase Dephosphorylated MLC which turns off process
Name 2 systems that act as pro-contractile mechanism in signaling Protein Kinase C and Rho kinase system
What is MLCK a target for? cAMP signaling. cAMP is one of the mechanisms of relaxation. PKA can phosphorylate MLCK and sort of inhibit MLCK
Describe the receptor mechanism involving PLC Generates IP3 and DAG. IP3 enhances contractive apparatus and DAG is primary stimulator of PKC which leads to increase action of Ca
Describe SERCA pump Reuptake mechanism. Phosphorylated by cAMP and cGMP kinase which leads to more Ca pumped back into SR
Describe visceral/unitary smM May have gap junctions b/w cells. If there is no gap junctions mechanical connections will lead to contraction of cell due to contraction of adjacent cell.
Pacemaker cell of visceral smM First cell in stretching process that when muscle depolarizes it promotes contraction in adjacent cells. Then propogation
SNS-regulated smM Alpha and beta receptors. alpha1 and beta2 are primary. alpha receptors work in direction of increase force, sensitive to NE. beta works in decrease, sensitive to Epi
How does alpha1 receptor work? Via receptor operated release of Ca to generate force
How does beta2 receptor work? Biggest stimulus is epi activating adenylate cyclase to make cAMP. (beta is enhanced in vascular smM)
PSNS regulated smM Uses Ach and Ach acts on muscarine receptors, activate to increase force. Direct effect of smM is to work via ROC mechanism to increase the force
Tissue hormone regulated smM Endothelium is enriched with NO synthase and converts L-Arginine to NO. PGI2 is made in endothelium.
What channels do ENHF open? K channels that hyperpolarize and there is hydrogen peroxide
Metabolic Regulation Circulation deals with oxygen delivery attempting to match oxygen demand/use. You release lactate during anaerobic oxidation which activates smM to relax.