Efeito da administração do fosfato de potássio na concentração sérica de cálcio em ratos (in vivo)

Abstract

The evidences demonstrate that the inorganic phosphate increase is strongly associated with the weakness of the contractile mechanism, due to attractiveness with the ion calcium liberated by the sarcoplasmic reticulum and the formation of the calcium phosphate. Experimental studies related to the effect of the inorganic phosphate reacting with ion calcium, usually in vitro are accomplished, in other words, with reactions that could omit substances with interfere in the conditions in vivo during the muscular contraction. It is still necessary to observe the high concentration of inorganic phosphate drives the precipitation of calcium phosphate and if these reactions can be verified in vivo, as well as, to present a methodology that allows reproductibility for futures research projects that can associate this precipitation affects, or can not, the muscular contraction. This study order to evaluated the inorganic phosphate, induced through the injection of potassium phosphate in vivo, it causes precipitation with the calcium serum, generating the product denominated insoluble phosphate of calcium and, which ideal amount to be injected indeed for such a precipitation to happen in vivo. The protocol used in that procedure consisted of the use of intraperitoneal injection of potassium phosphate, in rats Wistar separated randon and equal distributed in seven groups of seven animals, where the Group I was denominated of control and injected 0,5 ml of physiologic solution (NaCl 0,9%) and the Groups II to VII with the following doses, respectively: 0,5, 1,5, 2,5, 5,0, 7,5 g e 10,0 mg/kg. After the injection of potassium phosphate, the blood was collected of the inferior cava vein and submitted the biochemical evaluation of the creatinin, urea, calcium and inorganic phosphate. The results demonstrated that after to the regression of analysis, none of the models was significant statistically (p0,05) to represent some urea variation and of the creatinin in function of the variations of the doses of inorganic phosphate. In relation to the inorganic phosphate, the model sigmoidal of four parameters presents an excellent adjustment degree to the data and with difference significant statistically among the doses of potassium phosphate (p<0,0147). The calcium serum presented difference significant statistically (p<0,0069) among the treatment it controls and the treatment that corresponds to the application of 5,0 mg/kg of phosphate potassium. From of that value there is a tendency to the stabilization of the presented answer, where we didn't find differences significant statistically among the doses of potassium phosphate. With these results we can conclude that the potassium phosphate is a substance capable to cause precipitation of calcium serum without any lesion in the animals and that the ideal amount of potassium phosphate to be injected for increase of the concentration of inorganic phosphate and decrease of the calcium serum is of 5,0 mg/kg, and you dose superiors or inferior don't present effects in the concentration of calcium serum due to precipitation with the inorganic phosphate.