Blocking T-type Ca2+ channels with efonidipine decreased plasma aldosterone concentration in healthy volunteers

Area of Science:

• Pharmacology
• Endocrinology
• Cardiovascular Research

Background:

• Efonidipine blocks both L- and T-type calcium channels.
• Previous in vitro studies showed efonidipine suppresses aldosterone secretion, while nifedipine does not.
• The in vivo effects of efonidipine and nilvadipine on aldosterone require investigation.

Purpose of the Study:

• To assess the in vivo effects of efonidipine and nilvadipine on plasma aldosterone concentration in healthy volunteers.
• To compare the effects of efonidipine and nilvadipine on hemodynamic and neurohormonal parameters.
• To elucidate the role of T-type calcium channels in aldosterone secretion.

Main Methods:

• A placebo-controlled study involving five healthy male volunteers.
• Administration of placebo, efonidipine (40 mg), or nilvadipine (2 mg).
• Measurement of hemodynamic parameters, plasma neurohormonal factors, and serum electrolytes before and after drug administration.

Main Results:

• Efonidipine and nilvadipine increased plasma renin activity and Angiotensin II but had minimal effects on blood pressure, pulse rate, ACTH, Na+, and K+.
• Efonidipine significantly decreased plasma aldosterone concentration (p=0.0407).
• Nilvadipine significantly increased plasma aldosterone concentration (p=0.0049), contrasting with efonidipine's effect.

Conclusions:

• Efonidipine decreases plasma aldosterone concentration in vivo, irrespective of increased plasma renin activity and Ang II.
• The findings suggest that T-type calcium channels play a significant role in aldosterone secretion in healthy humans.
• Efonidipine's distinct effect highlights its potential therapeutic value in conditions involving aldosterone excess.