Voltage-gated calcium channels mediate hypoxic vasoconstriction in the human placenta

Area of Science:

• Cardiovascular Physiology
• Fetal Development
• Vascular Biology

Background:

• Fetoplacental vessels uniquely constrict during hypoxia, unlike most vascular beds.
• Hypoxic fetoplacental vasoconstriction (HFPV) is implicated in intrauterine growth retardation.
• The precise mechanism of HFPV remains largely undetermined.

Purpose of the Study:

• To investigate the role of voltage-dependent calcium channels in HFPV.
• To determine if L-type calcium channel activation mediates hypoxia-induced vasoconstriction in fetoplacental vessels.

Main Methods:

• Isolated perfused human cotyledons were used to study HFPV.
• Experiments compared responses in the presence of nifedipine (an L-type channel inhibitor) versus a vehicle control.
• The effect of nifedipine on vasoconstriction induced by acute hypoxia was assessed.

Main Results:

• Nifedipine, an L-type calcium channel inhibitor, completely abolished HFPV even at low doses (1 nM).
• The vehicle control (diluted DMSO) did not inhibit the hypoxic vasoconstriction response.
• This indicates a critical role for L-type calcium channels in mediating HFPV.

Conclusions:

• Activation of L-type calcium channels is a crucial component of hypoxic fetoplacental vasoconstriction.
• Understanding this mechanism may offer insights into managing intrauterine growth retardation.