In Vitro Action of Matrix Metalloproteinases 2 and 9 Inhibitors on Na + /K + -ATPase, H + /K + -ATPase and PMCA Activities in the Osmoregulatory Epithelia of Climbing Perch ( Anabas testudineus Bloch)

Matrix metalloproteinases 2 and 9 (MMP2 and MMP9) are involved in the extracellular matrix (ECM) remodeling. We tested the short-term in vitro action of inhibitors of MMP2 and MMP9 on P-type ion transporter function in organ explants of climbing perch ( Anabas testudineus ) to understand how these ECM remodeling components influence the ion transporter function in the osmoregulatory epithelia of fish. Graded doses (10 -8 , 10 -7 and 10 -6 M) of inhibitors of MMP2 and MMP9 were administered in vitro to explants of gills, kidney and intestine, kept for either 15 or 30 min and the activities of P-type ATPase such as Na + /K + -ATPase (NKA), H + /K + -ATPase (HKA) and plasma membrane Ca 2+ -ATPase (PMCA) were quantified. We found that the inhibitors of MMP2 and MMP9 produced dose- and time-dependent modulation in the activities of NKA, HKA and PMCA in the tested tissue explants. Incubation of MMP2 and 9 inhibitors at the highest dose (10 -6 M) for 15 and 30 min produced substantial rise in NKA activity. Likewise, HKA activity that showed significant rise after incubation of 10 -7 and 10 -8 M inhibitors in gills and kidney explants, decreased at the lowest dose (10-8 M) of inhibitors. The lower doses of both inhibitors, while increasing PMCA activity in kidney and intestinal explants inhibited its activity in gill explant. These differential tissue-responsive actions of MMP2 and MMP9 inhibitors indicate that these ECM remodeling components can modify the function of the membrane-bound P-type ion transporters in the osmoregulatory tissues of fish.