Stimulate the proliferation and differentiation of hair follicle epithelial cells: Normal human hair follicle epithelial cells are cultured in minoxidil solutions of different concentrations. Minoxidil can stimulate the proliferation of hair follicle epithelial cells at micromolar concentrations. Minoxidil sulfate is an active metabolite that stimulates hair growth, and sulfate transferase activity is higher in hair follicles than in the epidermis and dermis. In vitro histological culture of rat vibrissae hair follicles and experiments using 35S-labeled cysteine to synthesize hair keratin has confirmed that both minoxidil and its sulfate have hair growth effects. In vitro experiments show that the effect of minoxidil sulfate is 14 times that of minoxidil. If a sulfotransferase inhibitor or sulfate scavenger is added, the hair growth effect of minoxidil can be inhibited. However, it has no effect on the effects of sulfate metabolites. Animal experiments show that minoxidil can increase the number of dermal papillae, hair matrix, outer hair root sheath and fiber cell synthesis around the hair, thereby prolonging the hair anagen phase.
Promote angiogenesis and increase local blood supply: Hair growth relies on the vascular network of the dermal papilla to supply nutrients. During different hair growth cycles, the mRNA expression of vascular endothelial growth factor is different. Vascular endothelial cell growth factor mRNA is strongly expressed in dermal papilla cells during the growth phase, but less expressed during the catagen and telogen phases. Experiments show that minoxidil increases the expression of vascular endothelial cell growth factor mRNA and protein in a dose-dependent manner, thereby promoting the formation of dermal papilla blood vessels and increasing local blood supply.
Opening potassium channels: Opening potassium channels is an important step in regulating hair growth. In vivo and in vitro experiments in animal models have shown that minoxidil is a potassium channel activator and can increase the permeability of potassium ions.