Phenylephrine이 토끼 유두근의 수축력과 활동전압에 미치는 영향 = Effects of Phenylephrine on the Contractility and Action Potential of the Rabbit Papillary Muscle

다국어 초록 (Multilingual Abstract)

In order to clarify the receptor types and mechanisms underlying the positive inotropic effect of phenylephrie on the mammalian ventricular myocardium, the action potential, its first derivatives and isometric contraction of the rabbit papillary muscle were recorded using a free transducer and glass capillary microelectronics filled with 3M KCI, and results were analyzed.
The results were as follows;
l. In normal Tyrode solution, the contractile force was increased with increments of phenylephrine concentration and maximum effect was reached at the stimulation frequency of 1 Hz in 10^-5 M phenylephrine.
2. In 22 mM K^+-Tyrode solution, the maximum rate of rise (Vmax) of action potential, overshoot and the duration oction potential were significantly increased with increments of phenylephrine concentration (10^-6 ~ 10^-4 M).
3. The negative inotropic effect induced by verapamil was reversed by phenylephrine.
4. Phentolamine (3x10^-6 M) shifted the dose response curve for phenylephrine to the right more than propranolol (10^-6 M) did.
The above results may be interpreted as follow;
The positive inotropic effect of phenylephrine is caused by increase in slow inward current (Ca^2+influx into the myocardial cell), and is mediated through α- and β-adrengergic receptors in the rabbit pailary muscle