Age-related changes in blood pressure, hematological values, concentrations of serum biochemical constituents and weights of organs in the SHR/Izm, SHRSP/Izm and WKY/Izm

Age-related changes in hematological values, serum biochemical constituents, and weights of various organs in both sexes of the Spontaneously Hypertensive (SHR/lzm), Stroke-prone SHR (SHRSP/lzm), and Wistar Kyoto (WKY/lzm) rat strains, bred under SPF conditions, were examined to obtain fundamental data. The body weights from 3-30 weeks and systolic blood pressure from 6-30 weeks in each strain were measured every week. At the ages of 8, 16, and 30 weeks, the hematological values (erythrocyte, hemoglobin, hematocrit, leucocyte, thrombocyte), serum biochemical constituents (total protein, GOT, GPT, ALP, BUN, creatinine, glucose, total Ca and phosphorus, and ionized Ca, Na, K, and Cl were measured. Also, the organs, brain, heart, lung, thymus, liver, spleen, pancreas, bilateral kidneys, adrenal glands, testes/ovaries, digestive tract, and muscle (soleus) were weighed. The age-related changes as well as the strain and sex differences in each measured item were examined. The body weights of each strain increased, but rate of the increase was less in SHR and SHRSP, and was lowest in SHRSP. The blood pressure of SHR and SHRSP elevated with age, and showed higher in SHRSP than SHR, while that of WKY did not change. There were many strain differences in most measured items at each time point, particularly at 30 weeks. In SHRSP, high values of BUN, creatinine, total and ionized Ca, weights of brain, heart, liver, kidney and digestive duct were observed at most time points indicating that this strain's abnormality of calcium metabolism may be related to functions of the kidney and digestive duct as well as hypertension.