Abstract

Vanadate ion (VO₄^3-) is an established inhibitor of alkaline phosphatase (ALP) and inorganic phosphate transport across biologic membranes. The concentration-dependent effects of Co²⁺ and VO₄^3- on rat kidney ALP activity were carried out over a range of 3.33 – 25.67 mM p–NPP concentrations. The investigation revealed Co²⁺ as an activator of rat kidney ALP, while vanadate inhibited the enzyme. The activatory effect of cobalt ion on ALP was compared with that of magnesium ion when vanadate-inhibited ALP was exposed to both cobalt and magnesium ions at both 2 and 4 mM concentrations. The results revealed that cobalt ion at these concentrations significantly reversed (P < 0.05) vanadate inhibition of rat kidney ALP activity while magnesium ion was significantly deficient (P < 0.05) in this regard. In the light of the foregoing, cobalt may be a better activator of rat kidney ALP in the presence of inhibitors of ALP. This reversal of ALP inhibition by Co²⁺could be employed as a protector with a potential physiological relevance in cells.

Key words: Cobalt, vanadate inhibition, alkaline phosphatase.