Anesth Pain Med.  2019 Oct;14(4):429-433. 10.17085/apm.2019.14.4.429.

The relaxant effect of nicardipine on the isolated uterine smooth muscle of the pregnant rat

• Kim DJ
• Hwang MH
• An TH
• Jung KT

• KMID: 2465341
• DOI: http://doi.org/10.17085/apm.2019.14.4.429

Abstract

BACKGROUND
Nicardipine, a calcium channel blocker, is used to treat hypertension in pregnancy or preterm labor. The current study was conducted to investigate the relaxant effects of nicardipine on the isolated uterine smooth muscle of the pregnant rat.
METHODS
We obtained uterine smooth muscle strips from pregnant female SD rats. After uterine contraction with oxytocin 10 mU/ml, we added nicardipine (10⁻¹² to 10⁻⁸ M) accumulatively every 20 min. We recorded active tension and frequency of contraction, and calculated ECâ‚… (effective concentration of 5% reduction), ECâ‚‚â‚…, ECâ‚…â‚€, EC₇₅, and EC₉₅ of active tension and frequency of contraction using a probit model.
RESULTS
Nicardipine (10⁻¹² to 10⁻⁸ M) decreased active tension and frequency of contraction in a concentration-dependent manner. The ECâ‚…â‚€ and EC₉₅ of nicardipine in the inhibition of active tension of the uterine smooth muscle were 2.41 × 10⁻¹â° M and 3.06 × 10⁻⁷ M, respectively. The ECâ‚…â‚€ and EC₉₅ of nicardipine in the inhibition of frequency of contraction of the uterine smooth muscle were 9.04 × 10⁻¹¹ and 4.18 × 10⁻⁷ M, respectively.
CONCLUSIONS
Nicardipine relaxed and decreased the frequency of contraction of the uterine smooth muscle in a concentration-dependent pattern. It might be possible to adjust the clinical dosage of nicardipine in the obstetric field based on our results, but further clinical studies are needed to confirm them.

Keyword

Nicardipine; Rat; Relaxation; Smooth muscle; Uterine contraction; Uterus

MeSH Terms

Animals
Calcium Channels
Female
Humans
Hypertension
Muscle, Smooth*
Nicardipine*
Obstetric Labor, Premature
Oxytocin
Pregnancy
Rats*
Relaxation
Uterine Contraction
Uterus
Calcium Channels
Nicardipine
Oxytocin

Figure

• 

  Fig. 1 Probability of inhibition of active tension of the pregnant rat uterine smooth muscle according to the concentration of nicardipine (M). Horizontal bars show 95% confidence interval for the efficient concentration of nicardipine in reducing contractility of uterine smooth muscle as 50% and 95% of probabilities (EC50 and EC95), respectively. EC: effective concentration.

• 

  Fig. 2 Probability of inhibition of the frequency of contraction in the pregnant rat uterine smooth muscle according to the concentration of nicardipine (M). Horizontal bars show 95% confidence interval for the efficient concentration of nicardipine in reducing contractility of uterine smooth muscle as 50% and 95% of probabilities (EC50 and EC95), respectively. EC: effective concentration.

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