Novel and Established Potassium Channel Openers Stimulate Hair Growth In Vitro: Implications for their Modes of Action in Hair Follicles

Gareth C. Davies, M. Julie Thornton, Tracey J. Jenner, Yi-Ju Chen, John B. Hansen, Richard D. Carr, Valerie A. Randall
2005 Journal of Investigative Dermatology  
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 þ inward rectifier subunits, Kir6.X, giving differing sensitivities to regulators. Therefore, the in vitro effects of established
more » ... ium 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 lM, po0.001), NNC 55-0118 (1 mM, po0.01; 0.1, 10, 100 lM, po0.001), and diazoxide (10 lM, po0.01) increased growth. Tolbutamide (1 mM) inhibited growth (po0.001) and abolished the effect of 10 lM minoxidil, diazoxide and NNC 55-0118; glibenclamide (10 lM) had no effect, but prevented stimulation by 10 lM minoxidil. Phenol red stimulated growth (po0.001), 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.
doi:10.1111/j.0022-202x.2005.23643.x pmid:15816824 fatcat:m25hios2xjhkrbq2p7pqocthza