Rafael Peñafiel

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The intracellular levels of polyamines, polycations implicated in proliferation, differentiation and cell survival, are regulated by controlling their biosynthesis, catabolism and transport. Antizymes and antizyme inhibitors are key regulatory proteins of polyamine levels by affecting ornithine decarboxylase, the rate-limiting biosynthetic enzyme, and(More)
Ornithine decarboxylase antizyme inhibitors, AZIN1 and AZIN2, are regulators and homologous proteins of ornithine decarboxylase (ODC), the rate limiting enzyme in the biosynthesis of polyamines. In this study, we have examined by means of real-time RT-PCR the relative abundance of mRNA of the three ODC paralogs in different rodent tissues, as well as in(More)
Agmatine (4-aminobutylguanidine), a dicationic molecule at physiological pH, exerts relevant modulatory actions at many different molecular target sites in mammalian cells, having been suggested that the administration of this compound may have therapeutic interest. Several plasma membrane transporters have been implicated in agmatine uptake by mammalian(More)
The role of polyamines in renal physiology is only partially understood. Moreover, most of the data on the enzymes of polyamine metabolism come from studies using whole kidneys. The aim of the present study was to analyze the mRNA abundance of the genes implicated in both the polyamine biosynthetic and catabolic pathways in different renal zones of male and(More)
Antizymes and antizyme inhibitors are key regulatory proteins of polyamine levels by affecting ornithine decarboxylase and polyamine uptake. Our previous studies indicated a metabolic interplay among polyamines, histamine and serotonin in mast cells, and demonstrated that polyamines are present in mast cell secretory granules, being important for histamine(More)
The administration of l-arginine hydrochloride has been used for testing pituitary secretion in humans, and as an experimental model for induction of acute pancreatitis in rats and mice. Whereas in the first case, the administration of the amino acid is associated with hiperkalemia, in the model of acute pancreatitis no data are available on possible(More)
Ornithine decarboxylase (ODC) is the key enzyme in the polyamine biosynthetic pathway. ODC levels are controlled by polyamines through the induction of antizymes (AZs), small proteins that inhibit ODC and target it to proteasomal degradation without ubiquitination. Antizyme inhibitors (AZIN1 and AZIN2) are proteins homologous to ODC that bind to AZs and(More)
The influence of different neural systems that modulate GnRH secretion by hypothalamic neurons was investigated in mice exposed to hypokalemic conditions, in which the pulsatile release of GnRH has been shown to be altered and associated with a significant decrease of plasma sex steroids. Our results demonstrate that the potentiation of the inhibitory(More)
Treatment of developing rats with monosodium glutamate (MSG) produces an increase of glutamate levels in the brain, being this elevation dependent on both route of administration and animal's age. The capacity of exogenous MSG to induce convulsions seems to be related to the rate of glutamate elevation in the brain, rather than to the absolute value of(More)
The content of free amino acids in the cerebrospinal fluid from 52 children in different age groups with febrile seizures were determined and compared to 88 age matched children without seizures. We found that the concentrations of some amino acids in CSF in the control group decreased slowly with age, reaching the concentrations found in adults at the age(More)