Biomedical subjects

M Munakata

Publications and source records attributed to M Munakata.

At least 109 records · Page 6Linked to original sources

PubMed1995

Increased susceptibility to silicosis and TNF-alpha production in C57BL/6J mice.

Toxic oxygen species and several proinflammatory cytokines are involved in the pathogenesis of silicosis. In order to understand whether factors that lead to susceptibility to ozone are also important in silicosis or not, we examined ozone-sensitive C57BL/6J mice and ozone-resistant C3H/HeJ mice as models of silicosis. We also analyzed the production of proinflammatory cytokines in both the acute and the chronic phases. On Day 2 after silica injection, the ozone-resistant C3H/HeJ mice showed significantly higher cellular responses as recognized by bronchoalveolar lavage (BAL) cell counts than did the C57BL/6J mice. In the chronic phase (Day 28 after silica injection), the ozone-sensitive C57BL/6J mice showed significantly greater responses to instilled silica judged by total protein and cell number in BAL fluid, hydroxyproline content, and histology than the ozone-resistant C3H/HeJ mice. TNF-alpha production by BAL cells after silica exposure was significantly higher in C57BL/6J mice than in C3H/HeJ mice in the chronic phase, whereas there was no significant difference in IL-1 alpha production between both strains of silica-injected mice. Also, the control C57BL/6J mice had significantly higher secretions of TNF-alpha than did the control C3H/HeJ mice in the acute phase. These results suggest that ozone-sensitive C57BL/6J mice are also more susceptible to silicosis than are ozone-resistant C3H/HeJ mice, and that the initial lower cellular responses and increase in TNF-alpha production may be related to the higher level of inflammatory and fibrotic response in the C57BL/6J mice.

Animals↗

PubMed1995

Smoking promotes insidious and chronic farmer's lung disease, and deteriorates the clinical outcome.

Although the prevalence of serum precipitating antibodies for farmer's lung disease (FLD) is lower in smokers than in nonsmokers and FLD predominates in nonsmokers, the affects of smoking on the clinical course of the disease is not known. We compared the clinical findings and the prognosis between 12 smokers (SM-FLD) and 31 non-smokers with FLD (NS-FLD). There was no difference in age, sex, working years on farm, clinical symptoms, laboratory findings, radiographic findings, between the two groups. However, for the type of onset on the first visit for FLD, "acute single episode" type was less common, and "recurrent" and "insidious onset" types were more common in SM-FLD than in NS-FLD (8.3 vs 58.1, 91.7 vs 41.9%, respectively, p < 0.05). Although working status and mask wearing status were not significantly different between the two groups after the diagnosis of FLD, patients with symptoms and/or radiographic abnormalities of FLD of more than 6 months were found more frequently in SM-FLD than in NS-FLD (66.7 vs 19.4%, p < 0.005). And also SM-FLD had more recurrences of FLD than NS-FLD after the initial diagnosis of FLD (1.58 +/- 1.56 vs 0.47 +/- 1.07, p < 0.05). SM-FLD tended to have lower % VC than NS-FLD (73.6 +/- 7.4 vs 88.5 +/- 3.9%, respectively, p = 0.06). Regarding the prognosis, the 10-year survival rates were 70.7% in SM-FLD, and 91.5% in NS-FLD (p < 0.05). These results suggest that smoking may make FLD insidious and chronic, and deteriorates the clinical outcome.

Adolescent↗

PubMed1995

Pressor effect of recombinant human erythropoietin: results of ambulatory blood pressure monitoring and home blood pressure measurements.

We investigated whether treatment of anemic hemodialysis patients with a low dose of recombinant human erythropoietin (erythropoietin) for a short period would increase their blood pressure. Ambulatory blood pressure monitoring and home blood pressure measurements were used to detect minute increase in blood pressure. Thirty-two patients with a hematocrit of 25% or less received erythropoietin at the dose of 4500 IU/week, by the intravenous route for 8 weeks. Erythropoietin increased the hematocrit from 20.9 +/- 2.1 to 26.2 +/- 2.1%. Erythropoietin elevated mean ambulatory blood pressure by 5 mmHg or more in two-thirds of patients (n = 20; pressor group), while it elevated home mean blood pressure by 5 mmHg or more in one-third of patients (n = 11). An increase in clinic mean blood pressure by more than 5 mmHg was observed only in one-fourth of patients (n = 7). Circadian variation of blood pressure (nocturnal fall and diurnal rise) had been attenuated in the patients of the pressor group before erythropoietin treatment and erythropoietin decreased the nocturnal fall of blood pressure further more. Erythropoietin elevated nocturnal blood pressure more than diurnal blood pressure. Therefore, the increase in blood pressure induced by erythropoietin was detected more reliably by ambulatory blood pressure monitoring. There was no relation between the change in hemoglobin concentration and the increase in ambulatory blood pressure induced by erythropoietin. Erythropoietin tended to decrease cardiac output and plasma volume while it increased total peripheral resistance. It also decreased plasma norepinephrine and vasopressin levels but did not affect other humoral factors. Although the pressor effect of erythropoietin treatment for 8 weeks at the dose of 4500 IU/week was not evident on clinic blood pressure measurements, any increase in blood pressure determined by ambulatory blood pressure should be treated carefully to reduce the risk of a cardiovascular complication in patients receiving hemodialysis.

Aldosterone↗

PubMed1995

[Role of viral infections in acute exacerbation of idiopathic interstitial pneumonia].

To evaluate the possibility that viral infections can trigger acute exacerbations of idiopathic interstitial pneumonia (IIP), we analyzed data from 105 patients with IIP. Acute exacerbation was defined as an increase in dyspnea, a decrease in PaO2 by more than 10 Torr, and worsening of chest radiographic findings within one month. Viral infection was said to be involved when patients had more than a 4-fold change in viral antibody titer or viral inclusion bodies in sputum during the acute exacerbation. Of the 105 patients with IIP, 30 had acute exacerbations. Among these 30 patients, viral infection was said to be involved in 11 (37%). Presumptive viruses were influenza virus (n = 6), parainfluenza virus (n = 1), herpes simplex virus (n = 1), RS virus (n = 1), and cytomegalovirus (n = 2). The levels of serum immunoglobulin A (IgA) before acute exacerbations were significantly lower (p < 0.05) in patients in whom viral infection was said to be involved. These results suggest that viral infection associated with a low value of serum IgA is an important trigger of acute exacerbations of IIP.

Aged↗

PubMed1995

[Acyclovir and guinea-pig airway smooth muscle].

Acyclovir, an anti-herpes virus drug, has been reported to affect aspirin-induced asthma (AIA). Acyclovir was reported to decrease the sensitivity to aspirin in some AIA patients. Although the hypothesis that AIA is related to viral infection has been stated, there is no proof that patients with AIA are infected with a specific virus. Therefore, whether the effect of acyclovir on AIA is due to an antiviral effect is not clear. We hypothesized that acyclovir directly affects airway smooth muscle. To test this hypothesis, we examined whether acyclovir can directly contract or relax guinea-pig airway strips, and whether it can modify contraction or relaxation induced with several agents in vitro. Acyclovir did not directly affect basal smooth muscle tone and did not affect the responses to leukotriene D4, prostaglandin E2, carbachol, or KCl. We conclude that acyclovir has no direct effect on the function of guinea-pig airway smooth muscle.

Acyclovir↗

PubMed1995

[A patient with cryptogenic organizing pneumonitis who presented with multiple patchy shadows].

A 62-year-old woman was admitted to our institution for abnormal shadows on a screening chest roentgenogram. An immunoelectrophoresis test on admission revealed a polyclonal gammopathy. In her bronchoalveolar lavage fluid, the percentage of lymphocytes was found to be high: 47%. These results indicated an abnormal immunological state. A chest X-ray film showed multiple patchy shadows in both lungs. A chest CT scan revealed that the shadows were distributed peripherally, and abutted the pleura. Before treatment, the lesions enlarged toward the hilum concentrically, and cleared from the pleural side. This change is characteristic of cryptogenic organizing pneumonitis. The pathological finding at open lung biopsy was organizing pneumonitis. Bronchiolitis obliterans was not pathologically recognized. The shadows on the chest X-ray film almost completely disappeared after treatment with predonisolone at a daily dose of 30 mg. We diagnosed this as a case of cryptogenic organizing pneumonitis with typical shadows.

Female↗

PubMed1995

[Factors influencing patterns of airway response after allergen challenge in patients with bronchial asthma].

We examined patterns of airway response of thirty nine asthma patients who had positive responses on allergen inhalation tests. Six types of inhaled allergens were used: house dust mite, animal, pollen, plant, mold, and others. Three patterns of responses were found: isolated immediate asthmatic response (IAR), immediate and late response (Dual), and isolated late asthmatic response (LAR). No relationship was found between the pattern of response and pulmonary function, airway sensitivity, IgE RIST titers, numbers of eosinophils, or concentration of inhaled antigens. Animal antigens tended to cause a dual response, and molds did only rarely. Ten of 39 challenged patients had an isolated LAR, half of which were caused by mold antigen inhalation. RAST scores were lower in isolated LAR than in other responses. Changes in the number and proportion of peripheral leukocytes during the challenge tests were also studied. Total leukocyte count had increased significantly in the isolated LAR group by 24 hours after the inhalation. These results suggest that the pattern of airway response after inhalation depended in part on the type of inhaled antigen, and that non-IgE mediated immune reactions have some role in the isolated LAR.

Adult↗

PubMed1995

[Autologous blood transfusion in cardiac surgery over 70-year-old patients].

We discussed the problems for autologous blood transfusion particularly in the preoperative blood donation about the patients over 70-year-old who underwent cardiac surgery in contrast with the younger patients. Following results were obtained: 1) Because aged patients have the tendency of anemia before predonation, full storage of blood donation could not be successed. 2 of 8 over 70-year-old patients were able to do the preoperative phlebotomy, and their mean volume were 355 gram as whole blood. On the other hand, 96% patients in younger group were phlebotomized preoperatively, and their mean value of storaged blood volume were 757 gram. 2) As the examinations about the iron-related parameters, not all aged patients were iron deficiency status. Their reticulocyte counts were nearly equal level to the younger group and plasma concentration of erythropoietin were higher in the aged patients than that in the younger group. These results indicate that erythropoiesis in the bone marrow was deteriorated in the aged patients. 3) In aged patients, all of them were required homologous blood transfusion at their perioperative terms. We thought that they have had the anemia before preoperation and our tolerable, allowable level to the postoperative anemia was not lower in the aged patients as against to the younger group. 4) We performed the autologous plasma donation with the membranous plasma separator added to the whole blood donation. It was easy and safe method, and circulatory indices were not changed before and after plasma-separation even in the aged patients. These autologous plasma were usefully administered as the volume expander postoperatively.

Aged↗

PubMed1995

[A case of mycosis fungoides with pulmonary involvement: effect of etoposide and prednisolone].

Persistent coughing and bloody sputum developed in a 75-year-old man with mycosis fungoides. Chest X-ray films on admission showed combined patterns of alveolar and interstitial shadows in both lung fields. Histological examination of the transbronchial lung biopsy specimen revealed patchy infiltration of mycosis fungoides cells in alveolar septa. VEPA chemotherapy was ineffective against skin lesions and caused bacterial pneumonia, but combined treatment with etoposide (200 mg, once a week) and prednisolone (30 mg, 3 days per week) resulted in remission. The patient has been taking oral etoposide and prednisolone regularly, and has been free of skin and pulmonary lesions for two years. Combined therapy with low-dose etoposide and prednisolone may be worth trying in cases of advanced mycosis fungoides with pulmonary involvement.

Aged↗

PubMed1995

Increased gain in baroreceptor-heart rate reflex in patients with primary aldosteronism.

OBJECTIVE: Reduced baroreflex sensitivity has been reported in several kinds of human hypertension. However, the nature of the baroreceptor-heart rate reflex in hypertension due to excess mineralocorticoid has never been fully explored. PATIENTS AND METHODS: Thirty patients with primary aldosteronism, 60 patients with essential hypertension (World Health organization stages I or II) and 45 normotensive subjects were enrolled. The groups did not differ in mean age. Blood pressure was similar between patients with primary aldosteronism and those with essential hypertension. Blood pressure (Finapres) and the RR interval (ECG) were monitored continuously at rest. The closed loop gain between systolic blood pressure and RR interval variabilities was used to measure the sensitivity of the baroreceptor-heart rate reflex. RESULTS: Baroreflex sensitivity in the group with primary aldosteronism was significantly greater than in the essential hypertensive group, but did not differ significantly between the group with aldosteronism and the normotensive group. Three to four weeks after removal of an adrenal adenoma (n = 25), both systolic and diastolic blood pressure were decreased significantly in the aldosteronism group but were still higher than in the normotensive group. The baroreflex sensitivity was reduced by about 40% after adrenalectomy compared to pre-operative values. The decrease in the baroreflex gain following adrenalectomy was correlated negatively with the decrease in systolic blood pressure (r = -4.00, P=0.05). CONCLUSION: These results demonstrate that hypertension due to excess mineralocorticoids is characterized by an increase in the gain of the baroreceptor-heart rate reflex. The reduction in baroreflex gain following adrenalectomy may delay the normalization of blood pressure.

Adolescent↗

PubMed1994

Regulation of K+ conductance by histamine H1 and H2 receptors in neurones dissociated from rat neostriatum.

1. The effects of histamine on dissociated neostriatal neurones of the rat were investigated in the whole-cell mode using the nystatin-perforated patch recording technique. 2. Histamine evoked a net inward current accompanied by a decrease in the membrane conductance at a holding potential (Vh) of -44 mV. This response was observed in neurones considered to be interneurones based on morphology, membrane properties and the responsiveness to acetylcholine. 3. A net inward current evoked by 10(-8) to 10(-6) M histamine was inhibited in a concentration-dependent manner by the H1 receptor antagonists, pyrilamine and triprolidine. The H1 receptor agonists, 2-methylhistamine and 2-thiazolylethylamine, mimicked the histamine response, indicating that this response was mediated by the H1 receptor. 4. Histamine, at high concentrations between 10(-6) and 10(-5) M, evoked an additional net inward current with a decrease in the membrane conductance, which was inhibited by the H2 receptor antagonists, cimetidine, ranitidine and famotidine. The H2 receptor agonist, impromidine, partially mimicked the response. Thus, this additional current was considered to be mediated by the H2 receptor. 5. The reversal potentials for H1 and H2 receptor-operated currents shifted 56.9 and 59.3 mV for a 10-fold change in [K+]o, respectively, suggesting that these currents were carried by K+. 6. An analysis of change in current fluctuations mediated by H1 and H2 receptors suggested that the unitary current amplitudes of K+ channels linked to H1 and H2 receptors were 0.29 +/- 0.06 (n = 4) and 0.27 +/- 0.07 pA (n = 4), respectively. There was no significant difference between these values. The estimated mean life times (tau) for both channels were also identical (1.1 ms). 7. It was concluded that histamine reduces K+ currents in neostriatal interneurones and that both H1 and H2 receptors are involved in the response.

Animals↗

PubMed1994

Altered frequency-dependent characteristics of the cardiac baroreflex in essential hypertension.

Blood pressure (BP) oscillations contain rhythmic components of low-, mid-, and high-frequency bands (0.02-0.06, 0.07-0.14, 0.15-0.40 Hz, respectively). Baroreceptors may sense each BP oscillation and induce a buffer reaction. To clarify the frequency-dependent baroreflex response and its possible alteration in patients with high BP, both BP (Finapres) and the RR interval (electrocardiogram) were continuously monitored in untreated patients with essential hypertension (EH) (n = 52) and normotensive subjects (NT) (n = 43). The magnitude and phase response of cardiac beats to BP oscillations were examined by transfer function analysis. Spontaneous baroreflex sensitivity was assessed by linear regression analysis of the BP and RR oscillations. The heart rate responded linearly to BP oscillations in more subjects at mid- and high-frequency bands (83% or more) than at the low-frequency band (60% or less). The phase was approximately zero at the high-frequency band and was consistently negative at the mid- and low-frequency bands. In general, all frequency gains were significantly and positively correlated with spontaneous baroreflex sensitivity. Each frequency gain was smaller in EH patients than in NT subjects, the high-frequency gain more so than the gains at the lower frequencies. In seven young EH patients, treatment with a beta 1-adrenoceptor selective blocker normalized the high-frequency gain and tended to increase the gains at the lower frequencies. These results suggest that the spontaneous baroreflex modulates RR oscillations over a broad frequency range from 0.02 to 0.40 Hz; the effect was most marked at frequencies higher than 0.07 Hz. Furthermore the frequency-dependent characteristics of the cardiac baroreflex were altered in essential hypertension partly because of an increased beta-adrenergic activity.

Adrenergic beta-1 Receptor Antagonists↗

PubMed1994

Accuracy and performance of the Terumo ES-H51, a new portable blood pressure monitor.

A high performance portable automatic sphygmomanometer, the Terumo ES-H51 (104 g, 58 x 22 x 92 mm), was newly developed for clinical use as a substitute for auscultation using a mercury sphygmomanometer. This device usually displays blood pressure (BP) values obtained by the Korotkoff sound method (K-method). However, when the device judges that BP values obtained by the K-method are inaccurate or unreliable, it substitutes automatically BP values obtained by the cuffoscillometric method (O-method). The accuracy and reliability of the device was tested by comparing it to the auscultation with the standard mercury sphygmomanometer. The mean difference between BP values obtained by the standard method and those obtained by the K-method were -0.7 +/- 2.9 mm Hg systole (mean +/- SD) and -0.3 +/- 2.6 mm Hg diastole, whereas the difference between the former and those obtained by the O-method were 0.3 +/- 5.7 mm Hg systole and 0.3 +/- 4.3 mm Hg diastole (n = 170). The agreement between the BP values obtained according to each of the two methods using the device and the standard method was within 5 mm Hg for 72% to 93% of both systolic and diastolic readings. Therefore, BP values measured by the ES-H51 are accurate. The ES-H51 is sufficiently small and light to be carried easily anywhere. The objective and reproducible BP information obtained by the present device would be useful in clinical practice.

Adult↗

PubMed1994

Muscarinic acetylcholine response in pyramidal neurones of rat cerebral cortex.

1. The effects of acetylcholine (ACh) on pyramidal neurons acutely dissociated from the rat cerebral cortex were studied in the whole-cell mode, by use of the nystatin-perforated patch recording configuration. 2. ACh induced a net inward current (IACh) accompanied by a membrane conductance decrease at a holding potential (VH) of -40 mV. IACh increased in a concentration-dependent manner with a half-maximum concentration (EC50) of 8.7 x 10(-7) M. 3. IACh mainly resulted from the suppression of the voltage- and time-dependent K+ current (M-current). 4. Muscarine and muscarinic agonists such as McN-A-343, oxotremorine and oxotremorine-M mimicked the ACh response. The potency was in the order of oxotremorine-M > McN-A-343 > or = muscarine > oxotremorine. 5. Pirenzepine shifted the concentration-response curve for ACh to the right and the corresponding Schild plot yielded a pA2 value of 7.81. Other muscarinic antagonists also reversibly blocked IACh in a concentration-dependent manner. The inhibitory potency was in the order of atropine > 4-DAMP > pirenzepine > AF-DX-116. 6. IACh could be induced normally even after pre-incubation of dissociated neurones in external solution with 200 ng ml-1 pertussis toxin (PTX) for 8 h, whereas the inhibitory effect of ACh on high-voltage-activated Ca2+ channels was completely abolished by the PTX treatment.

Acetylcholine↗

PubMed1994

Establishing diagnosis of pulmonary malignant lymphoma by gene rearrangement analysis of lymphocytes in bronchoalveolar lavage fluid.

We report the successful application of gene rearrangement analysis to the lymphocytes obtained by bronchoalveolar lavage (BAL) for the diagnosis of pulmonary malignant lymphoma. A 45-yr-old female patient who had been suffering from back pain was shown to have macroglobulinemia and pulmonary infiltrative shadow by chest radiography. Transbronchial lung biopsy revealed a small B-cell infiltrate with monotypic immunoglobulin expression (IgM/kappa light chain), and malignant lymphoma was highly suspected. BAL was performed to evaluate the cell profiles. The phenotyping of lavaged lymphocytes by flow cytometry revealed that the major component of the lymphocytes was CD3-positive T cells, and that CD21-positive B cells accounted for only 10% of all lymphocytes. This result was contradictory to the immunohistochemical population of lymphocytes in biopsied specimens. However, gene analysis of lavaged lymphocytes revealed positive immunoglobulin heavy chain rearrangement and negative immunoglobulin light chain and T-cell receptor rearrangement, suggesting that B cells making up a minor population of lavaged lymphocytes were proliferating monoclonally. Thus, in this case, gene analysis was an effective procedure for detecting the origin of tumor cells and distinguishing monoclonality from reactive accumulations. To our knowledge, this case represents the first reported application of gene rearrangement analysis to cells obtained by BAL. The sensitivity and usefulness of this analysis for the accurate evaluation of pulmonary lymphoproliferative lesions, when applied to BAL cells, should be emphasized.

Bronchoalveolar Lavage Fluid↗

PubMed1994

In vivo, in vitro correlation of acetylcholine airway responsiveness in sensitized guinea pigs. The role of modified epithelial functions.

Many attempts have failed to correlate in vivo airway responsiveness with in vitro airway smooth muscle functions. We have reexamined this relation by taking account of airway epithelial functions in guinea pigs sensitized with inhaled ovalbumin (OA). In vivo responses were assessed by the provocative concentration of acetylcholine (ACh) required to double the airway opening pressure (PC200) under mechanical ventilation. In vitro responses were measured in a perfused whole-tracheal preparation. The negative logarithm of the molar concentration of ACh required to produce a 10% reduction in diameter was calculated both for epithelial-side stimulation (PC10(in)) and for serosal-side stimulation (PC10(out)). OA-sensitized guinea pigs showed significantly smaller log PC200 than control animals (0.51 +/- 0.07 and 0.81 +/- 0.10, respectively, p < 0.01). In in vitro study, there were variable differences in PC10(in) and PC10(out) in each animal. The difference in sensitivity between epithelial- and serosal-side stimulation (PC10(in-out)) showed a significant correlation in PC10(in) (r = 0.82, n = 9, p < 0.01) but not to PC10(out) (r = 0.39, p > 0.1), indicating that the variation in PC10(in-out) resulted from the changes in PC10(in). For in vivo-in vitro correlation, log PC200 correlated significantly with PC10(in) (r = 0.68, n = 9, p < 0.05) but not with PC10(out) (r = 0.18, p > 0.1). These results indicate that the sensitization by inhalation of OA produces increased airway responsiveness to ACh in vivo and that this airway responsiveness may be related, at least in part, to the altered airway epithelial functions.

Acetylcholine↗

PubMed1994

Gamma-interferon modifies guinea pig airway functions in vitro.

Cytokines produced by T-lymphocytes may have significant roles in the airway inflammation seen in bronchial asthma. Gamma interferon (IFN-gamma), a T-cell derived cytokine, is known to modify functions of both immune and non-immune cells. In this study, we investigated whether IFN-gamma can modify guinea pig airway functions in vitro. The isometric tension of guinea pig airway strips was measured in a tissue bath filled with Krebs-Henseleit solution. Contracting responses to carbachol and KCl, and the relaxing response to isoproterenol (ISO) were examined. Effects of IFN-gamma were examined by comparing responses of the strips incubated with or without IFN-gamma (1000 U.ml-1; 25,000 U.ml-1). Contracting responses to carbachol and KCl were not affected by the incubation with IFN-gamma other than slight increased in maximum contraction by carbachol after 5 hours incubation with 25,000 U.ml-1 of IFN-gamma. Both 1 and 5 h incubation of strips with 25,000 U.ml-1 IFN-gamma significantly increased the sensitivity to ISO (p < 0.01 and p < 0.05, respectively) without affecting maximum relaxation. The effect of IFN-gamma on ISO relaxation was abolished by the denudation of airway epithelium from strips, indomethacin (2 microM), and cycloheximide (70 microM) but not by N omega-nitro-L-arginine methyl ester (30 microM). In addition, heat-inactivated IFN-gamma and bacterial endotoxin (LPS, 0.625 pg.ml-1) had no effect on ISO relaxation. These results suggest that IFN-gamma is able to modify airway smooth muscle response to beta-adrenergic agonist by inducing release of prostanoids from airway epithelium.

Animals↗

PubMed1994

A high-salt diet alters circadian blood pressure rhythm in Dahl rats.

To determine whether salt loading and salt sensitivity are related to the circadian variation in blood pressure (BP), we studied the circadian rhythm of BP in Dahl rats. Thirteen Dahl salt-sensitive (Dahl-S) and 14 salt-resistant (Dahl-R) rats were fed a high- or low-salt diet after weaning. Mean arterial pressure (MAP) and heart rate (HR) were measured every 4 sec throughout 24 hr in freely moving rats, and the data obtained were analyzed quantitatively by the cosinor method. MAP mesor was significantly elevated in Dahl-S rats on a high-salt diet (SH), as compared with those on a low-salt diet (SL), but there was no difference in the MAP mesor between Dahl-R rats on a high-salt diet (RH) and those on a low-salt diet (RL). MAP amplitude was significantly greater and HR amplitude was smaller in SH rats than in SL rats; the amplitudes of MAP and HR in RH rats were similar to those in RL rats. MAP acrophase was significantly delayed in SH and RH rats as compared with SL and RL rats, respectively; the time delay in the MAP acrophase was not accompanied by a synchronized delay in HR acrophase. The time delay in MAP acrophase was greater in SH rats than in RH rats. These results indicate that salt loading influences the amplitude and acrophase of BP, and that the effect of salt loading on circadian BP rhythm is modulated by salt sensitivity.

Animals↗