Role of intracellular Ca2+ in endothelium-dependent contraction and relaxation of rabbit intrapulmonary arteries.
We examined whether Ca(2+) mobilizers induce endothelium-dependent contraction and relaxation (EDC and EDR) in isolated rabbit intrapulmonary arteries. Ionomycin (10(-7) M) and A-23187 (10(-7) M), both Ca(2+) ionophores, and thapsigargin (10(-6) M), an endoplasmic reticulum Ca(2+)-ATPase inhibitor, caused a contraction in the non-contracted preparations, and a transient relaxation followed by a transient contraction and sustained relaxation in the precontracted preparations. Endothelium-removal abolished the contraction and transient relaxation (EDC and EDR) but not sustained relaxation (endothelium-independent relaxation, EIR). In the noncontracted preparations, ionomycin-induced EDC was significantly attenuated by quinacrine (10(-5) M), manoalide (10(-6) M), both phospholipase A(2) inhibitors, indomethacin (10(-5) M) and aspirin (10(-4) M), both COX inhibitors, and ozagrel (10(-5) M), a TXA(2) synthetase inhibitor. In the precontracted arteries, EDR was markedly reduced by L-NAME (10(-4) M), a NOS inhibitor, and methylene blue (10(-6) M), a guanylate cyclase inhibitor, and was enhanced by indomethacin, aspirin and ozagrel, probably due to inhibition of EDC. ZM230487, a 5-lipoxygenase inhibitor, had no effect on EDR. EIR was not affected by L-NAME, indomethacin or ZM230487. Arachidonic acid (10(-6) M) evoked EDC sensitive to indomethacin and ozagrel. L-Arginine (10(-3) M) caused EDR sensitive to L-NAME in the ionomycin-stimulated preparations. In conclusion, Ca(2+) mobilizers cause EDC and EDR via production of TXA(2) and NO, respectively.
Tarumi
Tadatsugu
T
Pharmacology Division, Radioisotope Research Center, Kyoto University, Yoshida Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan. tarumi@kyoto-pharm.ac.jp
Shirahase
Hiroaki
H
Kanda
Mamoru
M
Nakamura
Shohei
S
Kurahashi
Kazuyoshi
K
D000818:Animals; D001241:Aspirin / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D008689:Methacrylates / Q000494:pharmacology; D008751:Methylene Blue / Q000494:pharmacology; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects / Q000378:metabolism*; D011796:Quinacrine / Q000494:pharmacology; D011817:Rabbits; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
D004791:Enzyme Inhibitors; D007476:Ionophores; D008689:Methacrylates; D013729:Terpenes; D000001:Calcimycin; D015759:Ionomycin; D019284:Thapsigargin; C045673:manoalide; D011796:Quinacrine; C034364:ozagrel; D001241:Aspirin; D002118:Calcium; D008751:Methylene Blue; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin