Capsazepine

Capsazepine(CPZ) at a concentration of 94.2 µg/ml (IC50 concentration of capsazepine) exhibits a statistically significant inhibition of osteoclast growth and proliferation^[2]. Capsazepine converts the NKA into Na-ATPase. CPZ inhibits K+-dependent activity but allows Na-ATPase associated with Na+ transport. CPZ has no effect on Na-ATPase measured in the absence of K+. CPZ also inhibits para-nitrophenyl phosphatase activity, albeit with a lower affinity. CPZ strongly reduces the steady-state EP level and the Na+ affinity for phosphorylation decreased 3-fold after CPZ treatment. In summary, CPZ blocks an Na+/K+ cycle in the NKA but leaves an Na+ cycle intact, reducing the transport stoichiometry of the pump^[3]. Capsazepine inhibits osteoclast formation and bone resorption in a dose dependent manner in bone marrow-osteoblast co-cultures and RANKL generated osteoclast cultures. Capsazepine also suppresses RANKL induced IκB and ERK1/2 phosphorylation and causes apoptosis of mature osteoclasts and also inhibits alkaline phosphatase activity and bone nodule formation in calvarial osteoblast cultures^[4].

The cells are plated and treated with different concentrations of the test compounds and allowed to proliferate for 72 h. After 72 h of proliferation the cells are fixed in 10% formalin saline (50 μl/well) for 30 min. Then the cells are stained with crystal violet (0.05% w/v) for 30 min. The wells are then washed thoroughly with distilled water to remove any unbound dye and destained with Sorenson's buffer (0.1 M sodium citrate in 50% ethanol, pH 4.2). The absorbance of the extracted stain is measured at 540 nm.

Capsazepine pre-treatment prevents the increase in respiratory system resistance and decreases the increase in tissue damping during endotoxemia. Capsazepine also attenuates lung injury by a reduction in the collapsed area of the lung parenchyma induced by lipopolysaccharide (LPS).