Lack of an effect of saxitonin on the contractility of isolated guinea-pig trachea, lung parenchyma and aorta.
The effects of saxitonin were investigated in guinea-pig tracheal rings, lung parenchymal strips and aorta rings. Tracheal rings were used both with epithelium present and with it removed. Aorta rings were used both with endothelium present and with it removed. Saxitoxin, 1 pM to 0.1 microM, did not alter the resting tension of either airway tissues or aorta. Also 0.1 microM saxitonin did not reduce tension of tracheal rings contracted by 10 microM carbachol, parenchymal strips contracted by 100 microM acetylcholine or by 10 microM histamine, or aorta rings contracted by 10 microM norepinephrine. Responses of tracheal rings to 0.03-10 microM carbachol added cumulatively were not altered by 0.1 microM saxitoxin (EC50 with epithelium: 1.11 +/- 0.48 microM control, 2.01 +/- 0.71 microM with saxitoxin; EC50 without epithelium: 2.83 +/- 0.55 microM control, 2.05 +/- 0.58 microM with saxitoxin). Also, 1 microM saxitoxin did not alter contractions of parenchymal stirps to cumulatively added acetylcholine (EC50: 3.47 +/- 1.06 microM, control; 3.98 +/- 1.19 microM with saxitoxin), histamine (EC50: 0.83 +/- 0.24 microM, control; 0.60 +/- 0.13 microM with saxitoxin); or of aorta strips to norepinephrine with endothelium (EC50: 1.78 +/- 0.80 microM, control; 0.74 +/- 0.21 microM with saxitoxin) or without endothelium (EC50: 2.18 +/- 0.78 microM, control; 1.42 +/- 0.62 microM with saxitoxin). Thus, saxitoxin did not significantly alter contractile activity of airways of large arteries in vitro.
Robinson
C P
CP
College of Pharmacy, University of Oklahoma, Oklahoma City 73190.
Franz
D R
DR
Bondura
M E
ME
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001011:Aorta; D002217:Carbachol / Q000494:pharmacology; D004727:Endothelium / Q000187:drug effects; D004730:Endothelium, Vascular / Q000187:drug effects; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D008168:Lung; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D012530:Saxitoxin / Q000494:pharmacology*; D014132:Trachea
D012530:Saxitoxin; D006632:Histamine; D002217:Carbachol; D000109:Acetylcholine; D009638:Norepinephrine