Involvement of the atrial natriuretic peptide in the reduction of arterial pressure induced by swimming but not by running training in hypertensive rats

AbstractThe aim of this study was to compare, under resting conditions, the influence of chronic training in swimming or running on mean arterial pressure (MAP) and the involvement of the natriuretic peptide system in this response. Two-month-old male spontaneously hypertensive rats (SHR) were divided into three groups—sedentary (SD), swimming (SW) and running (RN)—and were trained for eight weeks under regimens of similar intensities. Atria tissue and plasma atrial natriuretic peptide (ANP) concentrations were measured by radioimmunoassay. ANP mRNA levels in the right and left atria as well as the natriuretic peptide receptors (NPR), NPR-A and NPR-C, mRNA levels in the kidney were determined by real-time PCR. Autoradiography was used to quantify NPR-A and NPR-C in mesenteric adipose tissue. Both training modalities, swimming and running, reduced the mean arterial pressure (MAP) of SHR. Swimming, but not running, training increased plasma levels of ANP compared to the sedentary group (P<0.05). Expression of ANP mRNA in the left atrium was reduced in the RN compared to the SD group (P<0.05). Expression of NPR-A and NPR-C in the kidneys of the SW group decreased significantly (P<0.05) compared to the SD group. Although swimming increased 125I-ANP binding to mesenteric adipose tissue, displacement by c-ANF was reduced, indicating a reduction of NPR-C. These results suggest that the MAP reduction induced by exercise in SHR differs in its mechanisms between the training modalities, as evidenced by the finding that increased levels of ANP were only observed after the swimming regimen

Effects of Chronic Swimming Training and Oestrogen Therapy on Coronary Vascular Reactivity and Expression of Antioxidant Enzymes in Ovariectomized Rats - Figure 3

<div><p>Coronary expression of the antioxidant enzyme catalase.</p> <p>There were significant increased expression only in the trained group (OSW) when compared to OVX group (#p<0,05). Data are expressed as mean ± SEM; n = 3–5 animals per group.</p></div

Vasodilator response to growing concentrations of bradykinin (0,1–1000 ng).

<p>(A) Sham group had higher vasodilator response compared to OVX at 1000 ng (#p<0,05). (B) All trained/treated groups had a significant increased vasodilator response at the highest concentration (1000 ng) compared to OVX group (#p<0,05). In the OSW group, the vasodilator response was significant in the three highest concentration when compared to OVX group (#p<0,05). Data are expressed as mean ± SEM; n = 6–9 animals per group.</p

Expression of nitric oxide synthase isoforms in coronary arteries.

<p>(A) The endothelial isoform of nitric oxide synthase (eNOS) showing increased expression in OSW group compared to OE2 group (‡p<0,05) and (B) Inducible isoform of nitric oxide synthase (iNOS). In OSW group its expression was significantly decreased in relation to SH group (§p<0,05). Data are expressed as mean ± SEM; n = 3–5 animals per group.</p