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Effects of calcium channel blockers on cultured rat embryos
Y Ban1, T Nakatsuka, H Matsumoto
1Development Research Laboratories, Banyu Pharmaceutical Co., Ltd., Saitama, Japan.
Abstract:
Gestational day 11 rat embryos were cultured for 20 h in the presence of nifedipine (NIF), diltiazem (DIL) and verapamil (VER), and the effects of these calcium channel blockers on embryonic heart rate and gross morphology were examined. Reductions of embryonic heart rate were dose dependent and reversible. Effects on the heart rate were seen at doses as low as 0.3, 1 and 20 micrograms ml-1 for VER, DIL and NIF, respectively. Retardation of embryonic growth and morphological abnormalities, which were related to circulation defects, were seen at termination. The minimum doses to produce 100% effect on gross morphology were 2, 6 and 40 micrograms ml-1 for VER, DIL and NIF, respectively. These findings suggest that embryolethality seen in vivo studies is partly due to circulation defects and the associated morphological abnormalities in rats.
Insights
Calcium channel blockers like verapamil, diltiazem, and nifedipine reduce embryonic heart rate and cause developmental defects in rat embryos. These effects, linked to circulatory issues, suggest a cause for in vivo embryolethality.
Area of Science:
- Developmental toxicology
- Pharmacology
- Embryology
Background:
- Calcium channel blockers (CCBs) are widely used in cardiovascular medicine.
- Potential teratogenic effects of CCBs during early development require thorough investigation.
- Understanding CCB impact on embryonic development is crucial for risk assessment.
Purpose of the Study:
- To investigate the effects of verapamil, diltiazem, and nifedipine on embryonic development.
- To determine the dose-dependent effects of these calcium channel blockers on heart rate and morphology.
- To elucidate the role of circulatory defects in CCB-induced embryolethality.
Main Methods:
- Culturing of gestational day 11 rat embryos in vitro for 20 hours.
- Exposure to varying concentrations of verapamil, diltiazem, and nifedipine.
- Assessment of embryonic heart rate and gross morphological parameters.
Main Results:
- Dose-dependent and reversible reductions in embryonic heart rate were observed.
- Significant effects on heart rate occurred at low concentrations (0.3 µg/mL for verapamil, 1 µg/mL for diltiazem, 20 µg/mL for nifedipine).
- Embryonic growth retardation and morphological abnormalities, linked to circulatory defects, were noted at higher doses.
Conclusions:
- Calcium channel blockers can adversely affect rat embryo development.
- Circulatory defects and subsequent morphological abnormalities contribute to CCB-induced embryolethality in rats.
- These findings highlight the importance of considering CCB effects on embryonic development in vivo.