Oxygen and hydrogen on smooth muscle?

What are the effects of local oxygen and hygdrogen ion concentrations upon smooth muscle cells in pulmonary arterioles? In systemic arterioles? How does this effect pulmonary and systemic blood flow to capillary beds?
Answer:
Thats a real toughy!
For the increase in H+ concentration, that would lower the pH, of course. I would assume that this would decrease the rate of contraction, as anything which is not at the correct pH will not work, and so the smooth muscle will relax to both pulmonary and systemic. This would, of course, increase the flow of blood to pulmonary and systemic capillary beds.

For the O concentration? Well, thats even harder (as though I really answered the one above amazingly well!). I would say that an increase in O conentration would increase the amount of available ATP (it is made in the CAC cycle, citric acid cycle, and utilises Oxygen ions). This would increase the rate of contraction (and force, I guess), and therefore reduce the amount of blood flow to pulmonary and systemic circulations.

Obvioulsy decreasing the above (oxygen) would have the opposite effects to what I have just said. However, decreasing the H+ ion concentration would increase pH, and have the same effect - muscles not working as effectivley.

Hope this helps anyway, you dont have any answers!

Ashley

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