THE IMPACT OF HIGH SALT CONSUMPTION ON THE RENAL METABOLISM OF NAP-22 AND MARCKS, MAJOR PROTEIN KINASE C SUBSTRATES, IN SPONTANEOUSLY HYPERTENSIVE RATS

Objective. To investigate changes in NAP-22 messenger RNA (mRNA) expression level and the level of NAP-22 protein, as well as the level of MARCKS protein in kidney cells cytosole in spontaneously hypertensive rats after long-term high salt consumption which is a dietary factor of arterial hypertension (HTN). Design and methods. We evaluated SHR and WKY male rats before and after 10-day consumption of 1 % NaCl instead of drinking water. NAP-22 mRNA level was estimated using real time polymerase chain reaction (PCR), and the content of NAP-22 and MARCKS proteins was evaluated by dot immunoblotting or electerophoresis with subsequent immunoblotting. Results. In spontaneously hypеrtensive rats, the renal level of NAP-22 mRNA expression was significantly increased as compared with WKY group. High NaCl consumption definitely diminished NAP-22 mRNA expression in the both rat lines, however, its level was still higher in hypertensive rats than in normotensive rats. The NAP-22 protein level decreased, too. Similar changes were observed in the level of MARCKS protein in renal tissue. Conclusions. Unlike the long-term exogenous calcium deficiency, the salt load leads to the decrease of both RNA expression and the content in major protein kinase C (PK C) substrate proteins (NAP-22 and MARCKS). This indicates a potential change in the functioning of renal PK C system with an increased consumption of NaCl.

WKY

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