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F20 HUMAN HAIR FOLLICLES EXPRESS GENES FOR TWO FORMS OF THE SULPHONYLUREA
RECEPTOR OF POTASSIUM CHANNELS, ONLY ONE OF WHICH WOULD BE STIMULATED BY POTASSIUM
CHANNEL OPENERS USED CLINICALLY ATP-sensitive potassium (KATP) channel openers, e.g. minoxidil and diazoxide, stimulate hair growth, but their mechanisms are unclear. KATP channels involve a regulatory sulfonylurea receptor (SUR) found in SUR1, SUR2A and SUR2B forms giving differing sensitivities. Recently, we have shown stimulation of deer hair growth in vitro by drugs acting on two different receptors. The aim of this study was to investigate if these forms are expressed in human follicles. Human skin was treated with RNAlater(tm) stabilisation reagent to preserve mRNA by inhibiting ribonucleases. Individual anagen follicles were isolated by micro-dissection, pooled and total RNA extracted. RNA quality was checked before further purification to isolate poly(A)RNA; DNase treatment removed any contaminating DNA, before cDNA synthesis by reverse transcription. Reverse transcription-polymerase chain reaction (RT-PCR) was carried out using sets of primers designed to detect SUR1, SUR2A and SUR2B. RT-PCR reactions were also performed using primers for the highly expressed gene, ß-actin, to assess cDNA quality. PCR products were separated by gel electrophoresis and checked for appropriate sizes. The ß-actin gene was expressed in all samples, confirming cDNA quality. Bands were produced which correlated to SUR1 and SUR2B; no bands corresponding to SUR2A were detected These results indicate that human hair follicles express mRNA for two different forms of potassium channels with SUR1 and SUR2B sulphonylurea receptors. The SUR2B form, previously detected in human cultured dermal papilla cells (Li et al, 2001), would facilitate hair growth stimulation by minoxidil; however, the SUR1 form would not respond to minoxidil and has not previously been reported in human follicles.
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