The effects of the composition of cardioplegic solutions on coronary arterial strips and the additional effects of calcium antagonist(Verapamil) on cardioplegic solutions were studied with isolated canine coronary arterial strips.
The cononary arterial strips were dissected spirally from 3 main coronary arteries in 1-1.5 mm in diameter, 2-4 mm width, 20-35 mm length of Mongrel dogs.
Isometric active tension of coronary arterial strips recorded with Biocom isometric transducer and physiograph at a resting tension of 500-750 mg after 1 to 1(1/2) hr period of equilibration superfused in tyrode solution.
This study composed with group of effect of basic ionic component of cardioplegic solutions and group of experimental effects of various cardioplegic solutions with additives on coronary arterial strips.
The potassium brought about a dose dependent contraction of the coronary arterial strips over 8 mEq/L to 30 mEq/L above 18℃ in temperature.
The calcium had additive contraction of the coronary strips previously contracted by G-K(Glucose-potassium) solution over 0.6 mEq/L and as much as twice at 2.0 mEq/L in 37℃.
Addition of the magnesium to calcium chelated G-K solution with small dose and rela--ted beyond primary isometric tension level over 30 mEq/L infusion.
Simple G-K solution, St. thomas´ hospital solution, Bretschneider solution and Blood cardioplegic solution have contracted markedly the,.coronary strips near similary in spite -of the difference of their composition.
Addition of Verapamil 2.0 mg/L to the cardioplegic solutions abruptly diminished or absent the contracting effect of various cardioplegic solutions.
In most cases, the hypothermia slightly reduced vasoconstriction and enhanced vasodilatation.
The results suggest that the various potassium contained cardioplegic solutions with or without calcium brought about a contraction of the coronary arterial strips in similar pattern but the contraction effects were diminished with addition of magnesium or calcium antagonist, as well as hypothermia.
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