Novel and established potassium channel openers stimulate hair growth in vitro: implications for their modes of action in hair follicles

J Invest Dermatol. 2005 Apr;124(4):686-94. doi: 10.1111/j.0022-202X.2005.23643.x.


Although ATP-sensitive potassium (K(ATP)) channel openers, e.g., minoxidil and diazoxide, can induce hair growth, their mechanisms require clarification. Improved drugs are needed clinically. but the absence of a good bioassay hampers research. K(ATP) channels from various tissues contain subtypes of the regulatory sulfonylurea receptor, SUR, and pore-forming, K(+) inward rectifier subunits, Kir6.X, giving differing sensitivities to regulators. Therefore, the in vitro effects of established potassium channel openers and inhibitors (tolbutamide and glibenclamide), plus a novel, selective Kir6.2/SUR1 opener, NNC 55-0118, were assessed on deer hair follicle growth in serum-free median without streptomycin. Minoxidil (0.1-100 microM, p<0.001), NNC 55-0118 (1 mM, p<0.01; 0.1, 10, 100 microM, p<0.001), and diazoxide (10 microM, p<0.01) increased growth. Tolbutamide (1 mM) inhibited growth (p<0.001) and abolished the effect of 10 microM minoxidil, diazoxide and NNC 55-0118; glibenclamide (10 microM) had no effect, but prevented stimulation by 10 microM minoxidil. Phenol red stimulated growth (p<0.001), but channel modulator responses remained unaltered. Thus, deer follicles offer a practical, ethically advantageous in vitro bioassay that reflects clinical responses in vivo. The results indicate direct actions of K(ATP) channel modulators within hair follicles via two types of channels, with SUR 1 and SUR 2, probably SUR2B, sulfonylurea receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Coloring Agents
  • Deer
  • Diazoxide / pharmacology
  • Hair Follicle / drug effects*
  • Hair Follicle / growth & development*
  • Hair Follicle / physiology
  • Hydrogen-Ion Concentration
  • Hypoglycemic Agents / pharmacology
  • Ion Channel Gating / drug effects
  • Male
  • Minoxidil / pharmacology*
  • Organ Culture Techniques
  • Phenolsulfonphthalein
  • Potassium Channels / physiology*
  • Tolbutamide / pharmacology
  • Vasodilator Agents / pharmacology*


  • Coloring Agents
  • Hypoglycemic Agents
  • Potassium Channels
  • Vasodilator Agents
  • Minoxidil
  • Tolbutamide
  • Phenolsulfonphthalein
  • Diazoxide