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S T Zhu

Publications and source records attributed to S T Zhu.

8 recordsLinked to original sources
PubMed1996

Atrial natriuretic peptide blunts arterial baroreflex in spontaneously hypertensive rats.

We and other laboratories have reported that arterial baroreflex-mediated control of heart rate is blunted in spontaneously hypertensive rats (SHR) compared with normotensive controls. Recently, we reported that atrial natriuretic peptide (ANP) microinjected into the caudal nucleus tractus solitarii of SHR further blunts this defect. The present study tested the hypothesis that ANP modulates arterial baroreflex-mediated control of sympathetic nervous system activity. Nine-week-old, male SHR (n = 29) and normotensive Wistar-Kyoto control rats (n = 24) were instrumented for microinjection into the caudal nucleus tractus solitarii and for direct measurement of arterial blood pressure, heart rate, and lumbar sympathetic nervous system activity. After urethane- and alpha-chloralose-induced induced anesthesia, arterial baroreflex-mediated control of heart rate and lumbar sympathetic nerve activity was assessed during phenylephrine- (5 to 40 micrograms.kg-1.min-1) induced increases and sodium nitroprusside- (15 to 300 micrograms.kg-1.min-1) induced decreases in mean blood pressure before and after microinjection of ANP (50 ng) or monoclonal antibody to ANP (0.55 micrograms) into the caudal nucleus tractus solitarii. ANP reduced and the antibody enhanced the sensitivity of baroreflex-mediated control of both heart rate and lumbar sympathetic nerve activity in SHR but not in Wistar-Kyoto controls (P < .05). Arterial baroreflex sensitivity was unchanged with control microinjections of vehicle or mouse IgG in SHR. These data suggest that endogenous ANP in the caudal nucleus tractus solitarii may contribute to the development and/or maintenance of hypertension in SHR by blunting baroreflex-mediated control of sympathetic nervous system activity.

Animals↗
PubMed1995

Gender and dietary NaCl in spontaneously hypertensive and Wistar-Kyoto rats.

We recently reported that high dietary NaCl exposure significantly increases both daytime and nighttime mean arterial pressure in male spontaneously hypertensive rats (SHR) but only nighttime values in male normotensive Wistar-Kyoto rats (WKY). In the present study we used a telemetry monitoring system to evaluate the effects of high dietary NaCl exposure on diurnal variation of mean arterial pressure and heart rate in male and female SHR and WKY. After implantation of a radio-frequency transducer, rats were fed either high (8%) or basal (1%) NaCl diets for 2 weeks. High dietary NaCl ingestion significantly increased both daytime and nighttime mean arterial pressure in male SHR compared with males receiving a basal NaCl diet, resulting in greater 24-hour values (163 +/- versus 154 +/- 1 mm Hg, high versus basal NaCl diet; P < .05). High dietary NaCl ingestion significantly increased only nighttime blood pressure in male WKY, with no significant effect on 24-hour mean arterial pressure (102 +/- 2 versus 101 +/- 3 mm Hg, high versus basal). High dietary NaCl exposure did not affect daytime or nighttime mean arterial pressure in female SHR (24-hour mean arterial pressure, 144 +/- 2 versus 141 +/- 2 mm Hg, high versus basal NaCl diet). Twenty-four-hour mean arterial pressure tended to be lower in female WKY receiving a high NaCl diet than females ingesting a basal diet (101 +/- 3 versus 106 +/- 1 mm Hg), but the difference was not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[The effect of teeth arrangement in maxillary complete denture on the stress distribution of bone tissue--photoelastic stress analysis].

In this paper, we make a study about the effects of 6 different kind of arrangement of the 1st molar in maxillary complete denture on the stress distribution of bone tissue. In intercuspation position, it is well-distributed when the artificial teeth are arranged on the top of alveolar ridge. There are stress concentration in the bone tissue. When the long axis of the teeth incline bucally or the teeth migrate away from the ridge center line. When the ridges relation is disharmonious, it is better that the teeth incline do not over 30 degrees buccally and the teeth migration do not over 5 mm horizontally.

Alveolar Process↗
PubMed1990

[Risk of endogenous N-nitrosodimethylamine formed by dimethylamine in rats--precursors stability].

N-Nitrosodimethylamine (NDMA) is a potential carcinogen and present in our surroundings widely. NDMA can be formed by many precursors, Dimethylamine (DMA) is the most common precursor in food. To evaluate the risk of DMA nitrosation in vivo, so that men can do their best to reduce endogenous nitrosamine exposure, we carried out this research. This paper is the first part of our research. The stabilities of DMA and nitrite in the stomach were studied. DMA was stable and nitrite was decomposed at the speed of second-order reaction. The stabilities of nitrite in simulate gastric acid and in ascorbic (VC) solution also were studied. Nitrite decomposition in simulate gastric acid was very similar to the one in the stomach. VC solution at the equimolar with nitrite can decompose 53-79% of nitrite in one minute with shaking. We suggested that the efficiency of VC inhibiting endogenous nitrosation can be estimated on the basis of decomposing speed of nitrite and nitrosating speed by nitrite.

Animals↗