Abstract: Somatostatin (SST) is a peptide which biological effects are due to the interaction with five receptor subtypes (somatostatin1-5) which can be blocked by the antagonists, such as cyclo-somatostatin (cSSTA). The assay for ATPases was performed in synaptosomal membranes of rat cerebral cortex, basal Na+, K+ -ATPase activity was 18.0 ± 5.3 µmol Pi x mg. prot-1x h-1, there was not any changes by the presence of 10-9-10-6M SST, but SST 10-5M produced a significant increase in Na+, K+-ATPase activity. Besides Mg2+- ATPase activity was not modified by all SST concentrations employed. SST effects on ATPase activity was completely blocked by the previous addition of cSSTA, a somatostatin receptor antagonist, which is suggested that SST receptors could be involved in these effects.
Na+, K+ -ATPase activity was also studied in membranes isolated from adult rats which were administered with vehicle (saline) or L-NAME, a nitric oxide synthase inhibitor. When L-NAME was administered to rats during the postnatal period, it was observed an increase in Na+, K+-ATPase activity in the presence of 10-6 M SST to membranes prepared in the adulthood of those animals.
L-NAME was also administered to adult rats with the intention to prepare cortical membranes for [3H]-ouabain binding assay. The results showed a significant increase in [3H]-ouabain binding to membranes from L-NAME administered rats in the absence or presence of SST 10-6M. In conclusion the SST produced changes in ATPase activity according to the moment in which the L-Name had been administered to experimental animals.
Keywords: Nitric oxide, L-NAME; somatostatin; ATPase activity; high affinity [3H]-ouabain.
Title: Somatostatin Modifies L-NAME Effects on ATPase Activity
Author: María G. López Ordieres, PH. D., Alma Kemmling, Andrea Induni, María G. Bersier PH. D
International Journal of Life Sciences Research
ISSN 2348-313X (Print), ISSN 2348-3148 (online)
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