Vascular smooth muscle stuff

Question 1

What are the three ways that intracellular calcium can be increased in a smooth muscle cell?

Answer 1

1. Voltage-gated calcium channel in cell membrane
2. Ligand-gated calcium channel in cell membrane (ligand is hormone or neurotransmitter)
3. IP3-mediated opening of SR channels (kicked off by hormone or neurotransmitter binding to cell membrane receptors, leading to IP3 second messenger)

Question 2

What are three ways to decrease (resequester) intracellular calcium?

Answer 2

1. Calcium ATP-ase pump in plasma membrane
2. Sodium-calcium exchange pump (in plasma membrane) powered by sodium gradient
3. Another calcium ATP-ase pump, this one in SR membrane

Question 3

What type of sympathetic receptors are found in the vasculature of the heart?

Answer 3

B2

Question 4

The endothelium of a blood vessel releases factors that influence vascular smooth muscle contraction/relaxation. What are these factors and what are their effects?

Answer 4

1. prostacyclin - relaxation
2. nitric oxide - relaxation
3. endothelin-1 - contraction

All are released by endothelial cells lining lumen of vessel.

Question 5

What factors are released by parenchymal cells surrounding a blood vessel and what are their effects?

Answer 5

A metabolically active area of parenchyma releases H+, CO2, and K+ as part of its waste…these factors all have the effect of relaxing vascular smooth muscle (bring more blood and oxygen to the area, and speed up taking away the waste!)