The Dynamic Change Of Dendroapsis Natriuretic Peptide(DNP) Contents Both In The Plasma And Left Ventricle(LV) Of Spontaneously Hypertensive Rats(SHR)

ObjectiveTo evaluate the dynamic change of DNP contents both in the plasma and LV ofSHRs and to explore the possible role of DNP in the development of hypertension andleft ventricular hypertrophy (LVH).MethodsMale SHRs were served as experimental group, and were randomly divided intothe following subgroups4weeks,8weeks,12weeks and18weeks group(n=8).Male and age matched wistar kyoto rats(WKY) were as control group respectively(n=8). Blood pressure was measured by tail-cuff plethysmography.All rats weresacrified after anesthetized and weighted and haemospasia from abdominal aorta todetect the plasma concentration of DNP. Left ventricular mass index (LVMI)=leftventricular mass (LVM)/body surface area (BSA) was calculated. The expression anddistribution of DNP on LV were evaluated with immunohistochemical staining. Thecontents of DNP in both plasma and LV were measured with ELISA. The mRNA ofDNP in LV was assessed by Real-time PCR.Results1The SBP of SHRs was increased with aging (highest at18weeks)(p <0.05).There was no obvious difference between SHRs and WKYs at4week on SBP（p>0.05)，but SHRs showed higher SBP than WKYs at other three subgroupsrespectively(p<0.05). The LVMI of SHRs was increased with aging(p<0.05).Futhermore, SHRs showed higher LVMI than that in WKYs at eachsubgroups respectively (p<0.05).2The concentration of DNP in plasma of SHRs was increased with aging（p<0.01）.The content of DNP in plasma of each subgroup of experimental group was higher than that in each subgroup of control respectively (P<0.05).3(1) Immunohistochemical staining showed that DNP in LV was mainly distributedin the myocardial cells,endocardial endothelial cells，artery endothelial cells andartery smooth muscle cells. The expression of DNP on LV both in SHR and WKY ratwas decreased gradually (p<0.05). Furthermore, the expression of DNP on LV in eachSHR subgroup was lower than that in WKY subgroup respectively (p<0.05).(2) The content of DNP in LV was decreased with aging both in SHRs and WKYs（p<0.05）; each SHR subgroup of DNP in LV was lower than that in the WKYsubgroup (p<0.05).4The mRNA transcription of DNP was decreased with aging in both SHRs andWKYs (p<0.05). Furthermore, each SHR subgroup was lower than that in WKYsubgroup (p <0.01).Conclusions1The concentration of DNP in plasma of SHR was gradually increased with aging,it may play a role in the development of hypertention.2The expression of DNP in left ventricle of SHR was gradually decreased withaging,which may related to the development of LVH.