PubMed Health⌕ Search

Biomedical subjects

Y Hayashida

Publications and source records attributed to Y Hayashida.

At least 109 records · Page 6Linked to original sources
PubMed1990

Effects of centrally administered atrial natriuretic polypeptide on sympathetic nerve activity and blood flow to the kidney in conscious rats.

Effects of intracerebroventricular (i.c.v.) administration of atrial natriuretic polypeptide (ANP) on renal sympathetic nerve activity (RSNA) and renal blood flow (RBF) were examined in conscious rats. Administration of ANP had no appreciable effects on baseline RSNA and RBF. The pressor response induced by i.c.v. angiotensin II (AII) was attenuated by prior i.c.v. administration of ANP but no significant effect of ANP was observed on the AII-induced bradycardia and inhibition of RSNA. The result shows that centrally administered ANP has little effect on basal RSNA and RBF but it antagonizes the pressor response caused by AII without affecting induced changes in heart rate and RSNA.

Action Potentials↗
PubMed1990

Effects of denervation on the glomus cell membrane.

Trophic influences of the carotid nerve (CN) on carotid body (CB) glomus cells were studied by comparing the membrane potential (Em), input resistance (Ro) and voltage noise (Erms) of normal and 3-31-day denervated cells had more negative Ems. Higher Ros were recorded at 3 and 6 days. Erms sharply increased at 3 days, returned to normal at 6-15 days and was below normal at 31 days. A transmitter (ACh) and NaCN, producing histotoxic anoxia, were used for stimulation. These substances either depolarized or hyperpolarized innervated cells and increased or decreased voltage noise. Denervation selectively changed these patterns but only for a short time. ACh preferentially depolarized the cells, only at 3 days, whereas its effects on noise did not change. The Em responses to NaCN remained unaltered although at 3-6 days noise increases were smaller and depressions exaggerated. Possible reasons for these effects are discussed.

Acetylcholine↗
PubMed1990

Cardiovascular responses to some stressors in conscious rats.

The effects of several stressors on arterial blood pressure (BP), heart rate (HR), renal sympathetic nerve activity (RSNA) and renal blood flow (RBF) in conscious male rats were investigated. When conscious rats were exposed to smoke, the BP increased with marked decreases in HR and RBF, RSNA increased several times above the control level. During muscarinic blockade, smoke exposure reversed the HR response to an increase without any change in the RSNA. The results indicate that smoke exposure activates both the sympathetic and parasympathetic nervous systems. Whole body vibrations evoked increases in BP, HR and RSNA at frequencies less than 16 Hz. Higher frequency vibrations seemed to evoke no cardiovascular responses. It is suggested that cardiovascular responses to whole body vibration involve primarily the sympathetic nervous system.

Animals↗
PubMed1989

Inhibition of renal sympathetic nerve activity of anesthetized rats by intracerebroventricular administration of angiotensin II.

Effects of intracerebroventricular (i. c. v.) administration of angiotensin II (AII) on renal sympathetic nerve activity (RSNA), arterial pressure, and heart rate were examined in rats anesthetized with a mixture of urethane and alpha-chloralose. Administration of AII evoked an increase in arterial pressure and a decrease in RSNA with no significant change in heart rate. Prior i. c. v. administration of an AII antagonist, saralasin, greatly attenuated the pressor response and inhibition of RSNA induced by i. c. v. AII. Rats with sinoaortic denervation showed the same magnitude pressor response and decrease in RSNA as intact animals. The result suggests that central AII directly inhibits RSNA via AII specific receptors.

Action Potentials↗
PubMed1989

Comparison of effects of protein kinase C inhibitors on phorbol ester-induced CD4 down-regulation and augmentation of human immunodeficiency virus replication in human T cell lines.

The potent protein kinase C inhibitors staurosporine, H-7, and UCN-01 were investigated for their effects on 12-0-tetradecanoylphorbol-13-acetate (TPA)--mediated CD4 down-regulation and on the augmentation of human immunodeficiency virus (HIV) expression. Staurosporine was the most effective TPA inhibitor for both of these actions. Because of its high cytotoxicity, the effect of H-7 on augmentation of HIV expression could not be determined. UCN-01 had no cytotoxic effect, but caused only little inhibition of the augmentation of HIV expression.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1989

Some psychophysiological aspects of an Oriental method of stress reduction.

To summarize, SRM induces a state of relaxation as observed by psychological tests and by effects such as increases in the surface temperature of the hands. Such effects tend to occur from an early stage of training. Furthermore, SRM induces a state of "relaxed-alertness" as opposed to a drowsy state. A method to induce such a state of relaxation may be particularly suitable as a method of stress reduction in industrial settings, where a certain degree is vigilance is required. Currently, the authors are applying SRM in an industrial setting, hoping that such methods may result in stress reduction in a high-tech society.

Anxiety↗
PubMed1989

Changes in glomus cell membrane properties in response to stimulants and depressants of carotid nerve discharge.

Intracellular recordings were made from glomus cells in the excised, intact or sliced (150-200 microns) carotid body. Carotid nerve discharge was also recorded from intact preparations. Slices were prepared for visual (Nomarski) control of microelectrode impalement. Resting potential (Em), input resistance (Ro) and voltage noise (Erms) were measured in control conditions and in response to several stimulants (interruption of flow, hypoxic and histotoxic [NaCN]anoxia, hypercapnia, asphyxia and acidity) and depressants (alkalinity, cooling) of the carotid nerve sensory discharge. Different glomus cells responded differently to the same stimulus but significant trends were found. The more common responses to zero flow and anoxia (hypoxic and histotoxic) were depolarization (64%) and decreases in Erms (63%) and Ro (71%). When extracellular pH was varied from 8.5 to 5.0, the preponderant responses were cell depolarization, and increases in noise and input resistance as pH decreased. Consequently, cell depolarization induced by zero flow and anoxia tended to be accompanied by reduced Ro, whereas that induced by acidity generally showed increased Ro. Changes in voltage noise usually followed variations in Ro. When nerve discharge frequency was plotted against delta Em or delta Erms there were positive correlations during acid stimulation. However, these correlations were complex (parabolic) during flow interruption and anoxia: an increase in discharge occurred in response to cell depolarization and to hyperpolarization. These results suggest that hypoxia and hypercapnic or acidic stimuli act on glomus cells by different mechanisms. This finding is consistent with evidence obtained by recording carotid nerve discharges in intact animals.

Animals↗
PubMed1989

Renal sympathetic nerve activity and natriuresis during water immersion in conscious dogs.

The role of renal sympathetic nerve activity (RSNA) in the natriuresis and diuresis induced by head-out water immersion (WI) was studied in eight conscious female dogs. The dog was instrumented chronically with a stainless steel electrode for the measurement of RSNA and two catheters for the measurements of systemic arterial (Pa) and central venous (Pv) pressures. The WI caused an immediate reduction of RSNA by 43 +/- 7% (P less than 0.05), and this low level was sustained throughout a 120-min WI under thermoneutral conditions (37 degrees C). Urine flow and sodium excretion increased by 211 +/- 54 (P less than 0.05) and 240 +/- 122% (P less than 0.05), respectively, but creatinine clearance did not change significantly during WI. A step increase in Pa (by 10 +/- 4 mmHg, P less than 0.05) and Pv (by 10.0 +/- 0.8 mmHg, P less than 0.05) was observed also during WI. In another series of studies, renal denervations were performed 2-4 wk before the experiment in six of the same dogs. Dogs with renal denervation showed no significant changes in urine flow and sodium excretion in response to WI, whereas Pa and Pv increased by 10 +/- 7 and 10.0 +/- 2.0 mmHg relative to the control level, respectively. It is concluded that the reduction of RSNA observed during WI plays a major role in the natriuresis in the dog.

Animals↗
PubMed1989

Increase in sympathetic outflow by paraventricular nucleus stimulation in awake rats.

Our previous studies demonstrated that stimulation of the hypothalamic paraventricular nucleus (PVN) in anesthetized rats evoked a depressor response accompanied with a decrease in sympathetic outflow (H. Kannan, A. Niijima, and H. Yamashita, J. Auton. Nerv. Syst. 19: 83-86, 1987; H. Yamashita, H. Kannan, M. Kasai, and T. Osaka, J. Auton. Nerv. Syst. 19: 229-234, 1987). Because anesthesia may alter cardiovascular responses, we examined in conscious rats the effects of PVN stimulation on arterial pressure, heart rate, and renal sympathetic nerve activity. Electrical stimulation through chronically implanted electrodes evoked increases in arterial pressure and renal sympathetic nerve activity with a slight decrease in heart rate. The magnitude of responses was dependent on the frequency and the intensity of the stimulus. Latency of the excitatory response of the renal sympathetic nerve activity was approximately 70 ms. Microinjection of L-glutamate (0.5 M, 200 nl) into the PVN area also elicited increases in blood pressure and renal sympathetic nerve activity. These results suggest that activation of PVN neurons in conscious rats produces pressor responses due to an increase in the sympathetic outflow. These findings contrast with those obtained previously in anesthetized rats.

Action Potentials↗
PubMed1989

Renal sympathetic nerve activity and renal responses during head-up tilt in conscious dogs.

Renal sympathetic nerve activity (RSNA) was measured in conjunction with functional responses of the kidney during head-up tilt in eight conscious female dogs. A 40 degree head-up tilt resulted in a sustained increase in RSNA by 53 +/- 10% (P less than 0.05) relative to control level. Urine flow and osmolal and sodium excretions decreased significantly to a nadir of -55 +/- 4, -42 +/- 7, and -59 +/- 10%, respectively, whereas free water clearance and creatinine clearance did not change significantly during head-up tilt. The systemic arterial pressure (at kidney level) increased significantly from 110 +/- 4 to 129 +/- 6 mmHg, and central venous pressure decreased significantly from -0.7 +/- 0.5 to -7.6 +/- 0.6 mmHg. The chronic bilateral renal denervation, which was performed 2-4 wk before the experiment, abolished both the antidiuretic and antinatriuretic responses to heald-up tilt. These results indicate that an increase in RSNA plays a significant role in the decrease in urine flow and sodium excretion induced by 40 degree head-up tilt in conscious dogs.

Animals↗
PubMed1988

Thermographical analysis of the warmth of the hands during the practice of self-regulation method.

The changes in surface temperatures of the hands, and the permeation of warmth in the hands during self-regulation method (SRM), a new method of self-control, were studied in 5 trained subjects and in 5 beginners. Temperature changes were measured by thermography. Results indicated that both beginners and trained subjects showed similar significant increases in maximum hand temperatures during SRM, however, trained subjects showed significant increases during the control period as well. Further, both groups showed significant increases in the area of warmth permeation during SRM, however, trained subjects also showed a significant increase during the control period. There was a statistical difference between the two groups for the area of warmth permeation at both the end of the control period and the end of SRM. Thus, in SRM, although beginners seem to be able to raise their hand temperatures in a similar degree to trained subjects, the area of warmth permeation is significantly greater in trained subjects than in beginners. These results indicate that SRM is relatively easy to master for beginners. From these results, the technique of SRM, psychophysiological aspects of SRM and methods of self-control in general, and some issues regarding their clinical applications are discussed.

Adult↗
PubMed1988

Lymph flow dynamics into the thoracic duct of the rat.

Lymph flow into the thoracic duct of rats is reduced by 60% through immobilization with anesthesia. From this reduction, changes of the autonomic nervous activity by alpha-chloralose accounts for 20%. Pancuronium bromide blocking of the skeletal neuromuscular junction reduces lymph flow in the anesthetized rats by an additional 4%.

Anesthetics↗