[Effect of physical training by swimming on the arterial pressure, plasma and hypothalamo-post-hypophyseal vasopressin in genetically hypertensive rats of the Lyon strain].

The effect of a 5-week swimming training on systolic blood pressure (PAS) and vasopressin (AVP) and Neurophysins (NpT) concentration in the blood and content in the pituitary and the hypothalamus was studied in Lyon genetically hypertensive rats [LH] and in their controls: the normotensive [LN] and low blood pressure [LL] rats belonging to the 28th generation. Nine female rats of each group were trained 5 days a week for 5 weeks, starting with 2 h a day, with a 15 min increase every day, up to 6 h a day. The PAS was measured using an indirect plethysmographic technique one time a week during the whole training session. At the end of the training, the rats were decapitated. AVP and NpT were measured in blood, pituitary and hypothalamus, by radioimmunoassay (RIA). Hematocrit as well as plasma Na+, K+, protein and osmotic content were also measured. Results show that the training did not affect any of the studied parameters: mainly, there was no decrease in PAS or plasma AVP level in the hypertensive rats compared to the normotensive ones. The only difference was a lower AVP content in the pituitary of LH rats compared to LN (p less than 0.01), which is difficult to interpret. Our results shed doubt on the efficiency of a swimming training on the evolution of hypertension in the Lyon rat model.