Effect of high calcium diet on the development of high blood pressure in intact spontaneously hypertensive rats and in adrenalectomized spontaneously hypertensive rats treated with aldosterone

The current investigation was designed to study the effect(s) of high calcium diet on the development of high blood pressure (BP) in both young intact spontaneously hypertensive rats (SHRs) and in young adrenalectomized (ADX) male SHRs treated with aldosterone (ALDO). Weaned SHRs were fed either a control calcium diet (0.5% Ca as PO4) (CCaDiet), a high calcium diet (2.5% Ca, 0.5% as PO4 and 2% as CO3) (HCaDiet), or Agway ProLab rat food containing 2.5% Ca (HCaPLDiet). The HCaDiet significantly blunted the development of high BP in young intact SHRs (P less than 0.001; n = 8 to 10). At 6 weeks of age, BP was 117 +/- 2 mm Hg (HCaDiet) compared with 135 +/- 3 mm Hg (CCaDiet); by 12.7 weeks of age, BP was 192 +/- 4 mm Hg (HCaDiet) compared with 233 +/- 3 mm Hg (CCaDiet). Similar results were observed in age-matched SHRs fed the HCaPLDiet. The results show that subcutaneous infusion of ALDO (1.0 microgram/d, osmotic pumps) for 2 weeks to young ADX male SHRs raised on the CCaDiet caused a significant increase in systolic BP when compared with SHRs implanted with Sham pumps (P less than 0.001). High BP associated with ALDO infusion was attenuated by the HCaDiet (BP after 2 weeks was 138 +/- 8 mm Hg for the HCaDiet group compared with 200 +/- 5 mm Hg for the CCaDiet group, P less than 0.001; n = 4 to 6). The results show that the HCaDiet blunts the development of high BP in intact SHRs and may protect against the development of ALDO hypertension in ADX young SHRs.     

可溶性表氧化物水解酶与脂代谢

可溶性表氧化物水解酶(soluble epoxide hydrolase,sEH)在哺乳动物体内广泛存在。研究发现,sEH可以降解表氧二十碳三烯酸(epoxyeicosatrienoic acids,EETs)以及其他脂肪酸表氧化物。EETs具有广泛的心血管系统保护及抗炎作用,故sEH因其与心血管疾病的关系而受到关注。新近研究显示,sEH与脂质代谢密切相关,并与其C端水解酶区域和N端磷酸酶区域的不同活性有关。进一步深入探讨sEH的作用机制,将为研究脂质调节紊乱相关的代谢疾病提供一个新的治疗靶点。本文对sEH两端酶活性,及其与脂质代谢调节的研究进展予以综述。     

Thermal stress elevates the systolic blood pressure of spontaneously hypertensive rats

The effect of thermal stress on the systolic blood pressure of spontaneously hypertensive rats (SHR) and normotensive rats (WKY) of the Wistar/Kyoto strain was compared using our newly-developed indirect method which does not require heating of the animal to measure its blood pressure. The blood pressure of SHR increased significantly at 30°C and reached a maximum increase of about 20% at 32°C in 16 minutes in spite of the fact that the heart rate was decreased. In contrast to SHR, the systolic pressure of WKY did not change significantly after 30 minutes at 34°C or 36°C.     

Effect of diphenylhydantoin on blood pressure of spontaneously hypertensive rats

Diphenylhydantoin (DPH) has been shown to elicit direct peripheral vasodilatory effects in anaesthetised animals. Since spontaneously hypertensive (SH) rats exhibit many features similar to human essential hypertension, the effect of DPH on blood pressure of these rats was studied. DPH given orally for 5 days elicited dose-dependent fall in systolic blood pressure in conscious SH rats. In addition, repeated administrations of DPH increased the noradrenaline concentration in the hypothalamus. These results suggest that the central noradrenergic mechanisms might be involved in the hypotensive action of DPH in SH rats, probably at the supramedullary level.     

Increases in plasma trans-EETs and blood pressure reduction in spontaneously hypertensive rats

Epoxyeicosatrienoic acids (EETs) are vasodilator, natriuretic, and antiinflammatory lipid mediators. Both cis- and trans-EETs are stored in phospholipids and in red blood cells (RBCs) in the circulation; the maximal velocity (V(max)) of trans-EET hydrolysis by soluble epoxide hydrolase (sEH) is threefold that of cis-EETs. Because RBCs of the spontaneously hypertensive rat (SHR) exhibit increased sEH activity, a deficiency of trans-EETs in the SHR was hypothesized to increase blood pressure (BP). This prediction was fulfilled, since sEH inhibition with cis-4-[4-(3-adamantan-1-ylureido)cyclohexyloxy]benzoic acid (AUCB; 2 mg·kg(-1)·day(-1) for 7 days) in the SHR reduced mean BP from 176 ± 8 to 153 ± 5 mmHg (P < 0.05), whereas BP in the control Wistar-Kyoto rat (WKY) was unaffected. Plasma levels of EETs in the SHR were lower than in the age-matched control WKY (16.4 ± 1.6 vs. 26.1 ± 1.8 ng/ml; P < 0.05). The decrease in BP in the SHR treated with AUCB was associated with an increase in plasma EETs, which was mostly accounted for by increasing trans-EET from 4.1 ± 0.2 to 7.9 ± 1.5 ng/ml (P < 0.05). Consistent with the effect of increased plasma trans-EETs and reduced BP in the SHR, the 14,15-trans-EET was more potent (ED(50) 10(-10) M; maximum dilation 59 ± 15 μm) than the cis-isomer (ED(50) 10(-9) M; maximum dilation 30 ± 11 μm) in relaxing rat preconstricted arcuate arteries. The 11,12-EET cis- and trans-isomers were equipotent dilators as were the 8,9-EET isomers. In summary, inhibition of sEH resulted in a twofold increase in plasma trans-EETs and reduced mean BP in the SHR. The greater vasodilator potency of trans- vs. cis-EETs may contribute to the antihypertensive effects of sEH inhibitors.     

Dietary vitamin C supplementation lowers blood pressure in spontaneously hypertensive rats

In spontaneously hypertensive rats (SHRs) excess endogenous aldehydes bind sulfhydryl groups of membrane proteins, altering membrane Ca²⁺ channels and increasing cytosolic free calcium and blood pressure. The thiol compound, N-acetyl cysteine, normalizes elevated blood pressure in SHRs by binding excess endogenous aldehydes. Vitamin C can increase tissue cysteine and glutathione levels. The aim of the present study was to investigate whether a dietary supplementation of vitamin C can lower tissue aldehydes and blood pressure and normalize associated biochemical and histopathological changes in SHRs. Starting at 12 weeks of age, animals were divided into 3 groups of 6 animals each. Animals in the WKY-control group and SHR-control group were given a normal diet and the SHR-vitamin C group a diet supplemented with vitamin C (1000 mg/kg feed) for the next 9 weeks. After nine weeks, systolic blood pressure, platelet [Ca²⁺]_i, plasma insulin and liver, kidney and aortic aldehyde conjugates were significantly higher in SHR controls as compared to WKY controls and the SHR-vitamin C group. SHR-controls also showed smooth muscle cell hyperplasia in the small arteries and arterioles of the kidneys. Dietary vitamin C supplementation in SHRs lowered the systolic blood pressure, tissue aldehyde conjugates and attenuated adverse renal vascular changes.     

Glucuronidated quercetin lowers blood pressure in spontaneously hypertensive rats via deconjugation

Background

Chronic oral quercetin reduces blood pressure and restores endothelial dysfunction in hypertensive animals. However, quercetin (aglycone) is usually not present in plasma, because it is rapidly metabolized into conjugated, mostly inactive, metabolites. The aim of the study is to analyze whether deconjugation of these metabolites is involved in the blood pressure lowering effect of quercetin.

Methodology/Principal Findings

We have analyzed the effects on blood pressure and vascular function in vitro of the conjugated metabolites of quercetin (quercetin-3-glucuronide, Q3GA; isorhamnetin-3-glucuronide, I3GA; and quercetin-3′-sulfate, Q3''S) in spontaneously hypertensive rats (SHR). Q3GA and I3GA (1 mg/kg i.v.), but not Q3''S, progressively reduced mean blood pressure (MBP), measured in conscious SHR. The hypotensive effect of Q3GA was abolished in SHR treated with the specific inhibitor of β-glucuronidase, saccharic acid 1,4-lactone (SAL, 10 mg/ml). In mesenteric arteries, unlike quercetin, Q3GA had no inhibitory effect in the contractile response to phenylephrine after 30 min of incubation. However, after 1 hour of incubation Q3GA strongly reduced this contractile response and this effect was prevented by SAL. Oral administration of quercetin (10 mg/Kg) induced a progressive decrease in MBP, which was also suppressed by SAL.

Conclusions

Conjugated metabolites are involved in the in vivo antihypertensive effect of quercetin, acting as molecules for the plasmatic transport of quercetin to the target tissues. Quercetin released from its glucuronidated metabolites could be responsible for its vasorelaxant and hypotensive effect.     

Dietary vitamin E supplementation lowers blood pressure in spontaneously hypertensive rats

Pre-eclampsia, is the most common, pregnancy-associated pathological syndrome accompanied by a significant increase in collagen and sulphated glycosaminoglycans (GAGs) contents in the umbilical cord arteries (UCAs). Insulin-like growth factor-I (IGF-I) is expressed in most foetal tissues and it is involved in anabolic effects. It stimulates protein (mainly collagen) and GAG biosynthesis, cell proliferation and differentiation. Previously, we have found that pre-eclampsia is associated with an increase of IGF-I concentration in the umbilical cord blood. A family of IGF-I-binding proteins (BPs) modulates the activity of IGF-I. We demonstrated qualitative differences between BPs of normal and pre-eclamptic human umbilical cord (UC) serum and UC-tissues (UCA-wall and Wharton's jelly) by Western immunoblot analysis. All examined sera and tissues contained BP-1 and BP-5 as well lower molecular weight materials. The BP-2 was recovered from both control and pre-eclamptic sera, while it was not detected in the UC-tissues. Instead, lower molecular weight forms of BP-2 were found as judged by the anti-BP-2 antibody. The BP-3 was detected in sera, UCA and Wharton's jelly. The most distinct expression of BP-3 was found in the UCA. The pre-eclamptic UCA and Wharton's jelly contained additional BP-3-reactive material of lower molecular weight. The BP-4 was strongly expressed in pre-eclamptic UC-serum and the expression was decreased in pre-eclamptic UC-tissues, compared to respective controls. Ligand binding assay revealed that most of IGF-I was bound to 46 kDa region (typical for BP-3) in both control and pre-eclamptic sera and tissues. However, distinctly less IGF-I was bound in pre-eclamptic serum, distinctly more in pre-eclamptic UCA and no differences were found in pre-eclamptic Wharton's jelly, compared to controls. We demonstrated that both normal and pre-eclamptic UC-sera and tissues are able to degrade 46 kDa IGF-I-BP. The degradation may result in a decrease of IGF-I binding, contributing to increase in free IGF-I that may stimulate the cells to produce extracellular matrix (ECM) components. The specific BPs and their proteolytic modification in UC tissues may be important modulators of IGF-I action during foetal development.     

Genetic control of blood pressure in spontaneously hypertensive rats (SHR)

Genetic control of blood pressure in the SHR strain was studied by three separate experiments which consist of cross analysis between the SHR and Donryu, two-way selecton for high and low blood pressure levels, and successive backcrosses to the parental strains. The results obtained were as follows. 1. The data from genetic crosses between the SHR and Donryu showed the phenotype segregation ratio of 1:1 at the backcross and 1:2:1 at the F2 generation. 2. Two-way selection for high and low blood pressure levels was performed from the F2 generation onward. The separation between the two lines occurred immediately after the first selection. Thereafter, the difference increased gradually with generation. The blood pressure level at the seventh generation of selection became approximately equal to those of the parental strains. 3. Two types of the successive backcross were performed from the F1 hybrids by mating the males showing the highest blood pressure level to Donryu females and the females showing the lowest blood pressure level to SHR males on the other. Bimodality was observed in the distribution of blood pressure levels at each generation. Their phenotypic segregation ratios were accordant with 1:1 on the whole. At the intercross generation during successive backcrosses, a trimodal distribution was observed. 4. These results confirmed that the hypertensive trait of the SHR is regulated by a single major gene and other several genes with minor effect. A gene symbol ht was proposed for this major gene. Concurrently, a congenic strain having the ht gene on the genetic background of the Donryu was developed by the successive backcross system.     

Sexual dimorphism of blood pressure in spontaneously hypertensive rats is androgen dependent

Intact male and female spontaneously hypertensive rats showed a progressive increase in blood pressure with growth; male attained systolic blood pressure levels of 244 +/- 6 mmHg, and females 205 +/- 3 mmHg at age 22 weeks. Orchidectomy at age 4 weeks significantly attenuated the systolic blood pressure elevation in the male (195 +/- 4 mmHg at age 22 weeks), but ovariectomy at age 4 weeks had no effect on the development of hypertension in the female. The pattern of development of hypertension in orchidectomized males was the same as that in intact and ovariectomized females. Administration of testosterone propionate to gonadectomized rats of both sexes conferred a male pattern of blood pressure development. These results indicate that the sexually dimorphic pattern of hypertension in the spontaneously hypertensive rat is androgen dependent, rather than estrogen dependent. Plasma norepinephrine levels did not differ between the sexes, nor were they altered by gonadectomy or testosterone replacement, suggesting that the higher blood pressures in the intact male and androgen treated male and female SHR are not dependent on increased sympathetic outflow in the established phase of hypertension. Stores of norepinephrine in the posterior hypothalamic region were significantly greater in intact male rats and testosterone treated rats of both sexes than in intact or ovariectomized females, and were higher in the pons of intact female rats than in all other groups. These alterations in central catecholamine stores were not correlated with blood pressure. Further study is needed to assess the functional significance of these androgen mediated alterations in posterior hypothalamic neurons as a determinant of the androgen mediated sexual dimorphism of blood pressure in the spontaneously hypertensive rat.     

Chronic decrease of blood pressure by rat relaxin in spontaneously hypertensive rats

Relaxin is an ovarian polypeptide hormone which is present in large amounts in the rat during the second half of gestation. During this period, blood pressure declines markedly, especially in spontaneously-hypertensive rats (SHR). To test the hypothesis that relaxin might be implicated in this decrease in blood pressure, we infused the hormone in female non-pregnant rats by means of an osmotic mini pump. Our results show that intravenous infusion of purified rat relaxin (1.8 micrograms/day) markedly reduced systolic blood pressure for at least 5 or 6 days in SHR. This decrease was highly significant from 24 hours after the beginning of the infusion and remained significant after 5 days. Rat relaxin was ineffective in control Wistar-Kyoto rats (WKY). Infusion of purified porcine relaxin (3.0 micrograms/day) also diminished blood pressure in SHR, but the effect was less pronounced and developed more slowly, reaching statistical significance on the fourth day of infusion. SHR not receiving relaxin maintained their original systolic blood pressure throughout the experiment. These results indicate that relaxin is involved in the regulation of blood pressure during gestation.     

LVV-hemorphin-7 lowers blood pressure in spontaneously hypertensive rats: radiotelemetry study

Cardiovascular effects of LVV-hemorphin-7, a member of the family of fragments from beta-chain of human or bovine hemoglobin, were studied in conscious spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats by radiotelemetry. Intraperitoneal injection of hemorphin in a dose of 100 microg/kg significantly decreased blood pressure in SHR, whereas negligible effect was seen in normotensive WKY rats. Blood pressure changes were accompanied by reduction of heart rate. In conclusion, a direct effect of LVV-hemorphin-7 on blood pressure was demonstrated in SHR. These biologically active peptides could be involved in blood pressure regulation especially in hypertensive rats, but the precise mechanism should be elucidated.     

Alpha-lactorphin lowers blood pressure measured by radiotelemetry in normotensive and spontaneously hypertensive rats

Cardiovascular effects of subcutaneous administration of synthetic alpha-lactorphin, a tetrapeptide (Tyr-Gly-Leu-Phe) originally derived from milk alpha-lactalbumin, were studied in conscious spontaneously hypertensive rats (SHR) and in normotensive Wistar Kyoto rats (WKY) with continuous radiotelemetric monitoring. Alpha-lactorphin dose-dependently lowered blood pressure (BP) without affecting heart rate in SHR and WKY. The lowest dose which reduced BP was 10 microg/kg, and the maximal reductions in systolic and diastolic BP (by 23+/-4 and 17+/-4 mm Hg, respectively) were observed at 100 microg/kg dose in SHR. No further reductions were obtained at a higher dose of 1 mg/kg. There were no significant differences in the BP responses to alpha-lactorphin between SHR and WKY. Naloxone (1 and 3 mg/kg s.c.), a specific opioid receptor antagonist, abolished the alpha-lactorphin-induced reduction in BP and reversed it into a pressor response, which provides evidence for an involvement of opioid receptors in the depressor action of the tetrapeptide.     

A hypertensive substance found in the blood of spontaneously hypertensive rats

A substance has been obtained from the blood of spontaneously hypertensive rats which produces a hypertensive elevation of the blood pressure in normotensive rats. The substance is dialyzable and is associated with the erythrocyte membrane. It appears to be relatively long-lived in its effect on arterial pressure. The erythrocyte fractions that exhibit pressor activity also stimulate the in vitro uptake of calcium by aortas obtained from normotensive animals. This suggests that the hypertensive factor or related substances may influence the calcium metabolism of vascular tissue.     

Effect of high calcium diet on magnesium, catecholamines, and blood pressure of stroke-prone spontaneously hypertensive rats

To test the effect of a high dietary calcium intake on blood pressure, we fed stroke-prone spontaneously hypertensive (SHR-SP) and Wistar-Kyoto rats (WKY) diets containing (a) 0.25% Ca/0.08% Mg, (b) 4.0% Ca/0.02% Mg, and (c) 4.0% Ca/0.08% mg, beginning at 6 weeks of age. SHR-SP and WKY rats receiving 4% Ca with the lower Mg content had lower blood pressures, hypomagnesemia, and hypomagnesuria, and grew poorly. SHR-SP receiving 4% Ca and the higher Mg diet had blood pressures no different from those of rats receiving the 0.25% Ca diet, in spite of having lower body weights. Rubidium flux studies in erythrocytes were not influenced by Ca or Mg in the diets. Plasma phosphate values were moderately reduced in rats receiving 4% Ca diets. Epinephrine and norepinephrine values were higher in SHR-SP than in WKY rats. Norepinephrine increased with stress in both strains, independent of diet. Epinephrine values were lower in SHR-SP receiving the 4% Ca diets and showed less of an increase with stress compared to SHR-SP receiving the 0.25% Ca diet. After 26 weeks of diets, SHR-SP and WKY rats were given 0.9% NaCl in their drinking water. NaCl increased blood pressure in SHR-SP irrespective of Ca content of the diet. These data suggest that a high Ca diet influences Mg homeostasis and adrenal medullary function in SHR-SP. Further, SHR-SP appear resistant to any blood pressure lowering effect of Ca irrespective of NaCl intake.     

Antiserum to prolactin lowers blood pressure (BP) in spontaneously hypertensive rats

The role of PRL in the development of hypertension in the SHR was examined by administering PRL antiserum to neonatal SHR. On days 2-7 post partum, male SHR were injected with 50 microliters/day of either antiserum to PRL (which chronically lowers plasma PRL), normal rabbit serum (NRS), or 0.9% NaCl. Heart rate, BP, and body weight were measured biweekly on weeks 6-14 of age. Anti-PRL lowered BP vs. NaCl on weeks 6, 8, 12, and 14 (range 7-17 mm Hg lower). NRS animals showed BP differences from the NaCl group only on weeks 6 and 14, with no consistent effect. Heart rates fell during the study in the NaCl and anti-PRL groups but not in the NRS group. Anti-PRL and NRS groups had higher heart rates than did the NaCl group. Body weights did not differ between groups except on week 14, when the NRS group weighed less than the NaCl group. These results suggest that while PRL is involved in BP regulation in the SHR, it is not involved in the pathogenesis of the genetic hypertension seen in the strain. In addition, the results suggest that the serum treatment may have caused heart damage which led to an elevation in the heart rates of the serum-treated groups.     

Lupeol supplementation improves blood pressure and lipid metabolism parameters in stroke-prone spontaneously hypertensive rats

Supplementation with lupeol (0.67 g·kg(-1)) of the AIN-93M-based diet fed for 7 weeks to stroke-prone spontaneously hypertensive rats caused significantly decreased blood pressure as compared with a control group. Urinary 8-hydroxy-2'-deoxyguanosine was significantly lower in the lupeol group. Finally, lupeol suppressed the hepatic mRNA expression levels of the genes involved in triglyceride and cholesterol synthesis.     

Exercise training attenuates blood pressure elevation and adverse remodeling in the aorta of spontaneously hypertensive rats

OBJECTIVE: To observe the extracellular matrix modifications and quantify the structural alterations of the aortic wall in spontaneously hypertensive rats (SHR) submitted to an aerobic physical activity (PA) protocol. MATERIAL AND METHODS: Three groups of five rats each were studied: sedentary normotensive Wistar rats (SED-Wistar) and SHR (divided in SHR that underwent a 1 h/day 5 days/week PA for 20 weeks (EX-SHR) and those that were restricted to cage-bound activity (SED-SHR). RESULTS: BP was lower in EX-SHRs and SED-Wistar rats (-35%) than in SED-SHRs. This difference became significant from the 3rd week of PA. The wall thickness was smaller in the EX-SHR and SED-Wistar (-45%) than in the SED-SHR (p<0.0001). In EX-SHR group, oxytalan and elaunin fibers were more pronounced than in the other groups, while SED-SHR and SED-Wistar rats showed an equivalent appearance of aortic elaunin fibers. EX-SHR and SED-Wistar rats showed more than 65% greater smooth muscle nuclei numerical density per unit area than SED-SHRs while SED-SHRs showed more than 45% smaller surface density of lamellae than both EX-SHR and SED-Wistar rats. However, no quantitative differences were found in the aortic wall comparing EX-SHR and SED-Wistar rats. CONCLUSION: PA might alter the aortic wall remodeling to adapt the artery to a hyperkinetic blood flow resulting in alterations of the extracellular matrix modulation and vascular resistance.     

The effects of 19-nor-aldosterone on blood pressure of adrenalectomized spontaneously hypertensive rats

The relative hypertensinogenic potencies of recently synthesized 19-nor-aldosterone and its precursor 19-OH-aldosterone were assessed in comparison to that of aldosterone (Aldo) in young (6-week-old) adrenalectomized (ADX) spontaneously hypertensive rats (SHR). Infusion of 19-nor-aldosterone for 2 weeks by Alza mini-osmotic pumps caused significant, dose-dependent increases in the systolic blood pressure (BP) of young ADX SHR; dosages of 0.1 and 0.5 microgram/day raised the BP from 127 +/- 2 mmHg to 164 +/- 9 and 180 +/- 11 mmHg, respectively. During this period, control ADX SHR receiving vehicle only remained normotensive. Similar increases in BP were seen only with infusion of slightly higher dosages of Aldo (0.5 and 1.0 micrograms/day). In contrast, 19-OH-aldosterone infused at higher dosages (10 or 25 micrograms/day) caused little change in BP of ADX SHR. Full suppression of plasma renin activity (PRA) was observed with 0.1 and 0.5 microgram/day 19-nor-aldosterone, whereas Aldo caused similar decreases in PRA only at dosages of 0.5 microgram/day and higher. Interestingly, although infusions of 19-OH-aldosterone did not cause a significant change in BP, these dosages (10 and 25 micrograms/day) significantly suppressed PRA. These studies which show that 19-nor-aldosterone is equipotent to Aldo, and perhaps slightly more active in ADX SHR, indicate that 19-nor-aldosterone is a potentially important hypertensinogenic steroid.     

应用植入式遥测技术观察自发性高血压大鼠血压的昼夜波动

目的应用植入式遥测技术观察自发性高血压大鼠在清醒无束缚状态下血压昼夜波动变化。方法取8只SPF级3月龄雄性SHR大鼠,进行C50-PXT植入子植入手术,恢复7 d后,用遥测系统进行24 h连续清醒无束缚的血压监测,并用EMKA分析软件对动态血压心率均值、24 h血压心率趋势等指标进行分析。结果 3月龄的SHR大鼠血压和心律呈昼夜节律性变化,白昼阶段血压明显低于夜间阶段(P<0.01),血压在1∶30～2∶30和20∶30～21∶30时出现两个高峰期,14∶00～14∶30时出现一低谷期。其中夜间阶段平均收缩压为166.02 mmHg,两个收缩压峰值分别为172.13 mmHg和171.38 mmHg;白昼平均收缩压是162.73 mmHg,收缩压谷底值为155.73mmHg。而心率两个高峰期出现在1∶30～2∶00和20∶00～21∶00,高峰值分别为375.00次/分和373.26次/分;心率低谷出现在11∶00左右,谷底值为310.91次/分,白昼和夜间的平均心率分别为328.85次/分和346.05次/分。结论 3月龄的SHR大鼠血压和心律呈昼夜节律性变化,血压和心率在夜间出现两个高峰,白昼出现一个低谷,且夜间的平均血压和心率要高于白昼,SHR大鼠的血压和心率的节律变化与其活动有关。植入式遥测技术可准确反映SHR大鼠血压昼夜的节律性变化,有助于正确评价抗高血压药物的作用和高血压的生理机制研究。