Three phase contractile response of rabbit pulmonary artery to norepinephrine: influence of ruthenium red and calcium.
We recorded isometric contractile force of rabbit pulmonary artery after application of norepinephrine (50 microM), plotted semilogarithmic graphs of force development over time, and calculated rates of force development. The normal contractile response contained three phases: an initial fast, a short intermediate and a final slow. Correlation coefficients for each phase and differences between rates of force development of each phase were significant (P less than 0.05). Ruthenium red (1 mM) removed only the slow phase and significantly reduced the rates of the fast and intermediate phases. A calcium-free solution removed both the slow and intermediate phases and significantly reduced the rate of the fast phase.
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D000818:Animals; D002118:Calcium / Q000502:physiology*; D005260:Female; D066298:In Vitro Techniques; D007811:Lanthanum / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D011651:Pulmonary Artery / Q000187:drug effects; D011817:Rabbits; D012428:Ruthenium / Q000494:pharmacology*; D012430:Ruthenium Red / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects*
D012430:Ruthenium Red; D007811:Lanthanum; D012428:Ruthenium; D002118:Calcium; D009638:Norepinephrine