From bedside to bench: calcium gluconate is an effective treatment in hydrofluoric acid skin burns and reverses fluoride induced vasoconstriction in vitro

Objective: we studied the efficacy and safety of intra-arterial infusion of calcium gluconate on hydrofluoric acid (HF) skin burns treatment as well as on fluoride effects in rabbit aortic ring contraction in vitro and in modulation of intracellular Ca2+ concentration ([Ca2+]i) in vascular derived smooth muscle cells in culture. Methods: HF lesions could be hypothesized to be mediated by fluoride which was previously identified as a GTP binding proteins activator leading to inositol-phosphate accumulation and increase in [Ca2+]i. Calcium gluconate either topical or in intra-arterial infusion is considered the most effective clinical therapeutic approach. In this study, we examined a case series of patients with severe HF burns admitted to the Toxicology Unit of Careggi Florence Hospital, between 2005/2009 and treated with calcium gluconate both in local dermal application and in intra arterial infusion. Moreover, fluoride effects on rabbit aortic ring contraction in vitro and on modulation of [Ca2+]i in vascular derived smooth muscle cells in culture were evaluated. Results: five patients were admitted to the Toxicology Unit of Careggi Florence Hospital with a diagnosis of HF skin burns. They were treated with local dermal application and intra-arterial infusion of calcium gluconate. In all cases there was a complete restitutio ad integrum, with a maximum latency of two months and an average hospitalization time of six days. In in vitro experiments, sodium fluoride (10-30 mM) induced a contraction of rabbit aortic ring preparations (167±25%, n=4, p<0.05 one tailed t test) when compared to a standard contraction stimulated by KCL 80 mM. Calcium gluconate (50-100 mM) was able to decrease sodium fluoride induced contractile response (38±17%, n=4, p<0.05 one tailed t test). Similar results were obtained on sodium fluoride increase in [Ca2+]i in vascular derived smooth muscle cells in culture. Conclusion: intra-arterial infusion of calcium gluconate was confirmed a safe and effective therapeutic approach for wound healing and pain relief in HF skin burns. Calcium gluconate was also shown to be effective in reverting fluoride induced in vitro vasoconstriction. Thus, vasoconstriction may be suggested as a possible mechanism of HF induced skin damage.