Sympathetic activity and body mass index contribute to blood pressure levels

The purpose of this study was to clarify the relationships between obesity (BMI) and BP levels, leptin levels, sympathetic activity, and insulin sensitivity in a Japanese male population. In 912 young, non-diabetic, Japanese men with a wide range of BMI (16.5-33.6 kg/m2), blood pressure (BP), fasting plasma norepinephrine (NE), insulin and leptin levels were measured after an overnight fast. The cohort consisted of 603 normotensive and 309 hypertensive subjects. The study was carried out using a cross-sectional design. When the subjects were subdivided by tertile in relation to BMI, the 101 subjects in the heaviest group (BMI > 27.9 kg/m2) had a significantly higher systolic BP (p< 0.05) and pulse rate (p< 0.05) as well as higher NE (p< 0.01), insulin (p< 0.01), and leptin (p< 0.01) levels than 86 subjects in the leanest group (BMI < 22.2 kg/m2). In the whole cohort, BMI correlated with mean BP (p< 0.01), plasma NE (p< 0.05), insulin (p< 0.001) and leptin (p< 0.001). The mean BP correlated with BMI (p< 0.001), plasma NE (p< 0.01), insulin (p< 0.01) and leptin (p< 0.05). Plasma leptin levels correlated with fasting plasma insulin levels (p < 0.05), but not with plasma NE levels (NS). As analyzed by multiple regression analysis, only plasma NE (p< 0.05) and BMI (p< 0.001), but not plasma insulin levels, were significant, independent predictors of BP levels (r2=0.125, F= 10.51, p=0.0001). These results suggest that obesity (BMI) and heightened sympathetic nervous system activity contribute to BP elevation (hypertension).

The use of double-straight needle device in laparoscopic incisional and ventral hernia repair

Incisional and ventral hernias are good indications for laparoscopic hernia repair. A successful repair requires complete covering of the hernia defect, adequate tension of the prosthesis, and secure stapling by a hernia stapler. The authors introduce their technique using a double-straight needle device. This technique is easy and quick and achieves adequate fixation between the prosthesis and the abdominal wall, which reduces operating time and provides cosmetic benefit.

Weight gain-induced blood pressure elevation

This study was conducted to evaluate the mechanisms in weight gain-induced blood pressure (BP) elevation focusing, in particular, on the contributions of sympathetic nervous system activity, fasting plasma insulin, and leptin to BP levels. The study design was longitudinal with a cohort of 1897 men. BP, pulse rate, body mass index (BMI), fasting plasma norepinephrine (NE), insulin, and leptin were measured at 6 and 12 months in those 172 lean normotensive, 79 obese normotensive, 64 lean untreated hypertensive, and 38 obese untreated hypertensive men whose BMI increased >10% during the first 6 months. At entry, levels of BP, pulse rate, plasma NE, insulin, and leptin in obese subjects, regardless of BP status, were significantly greater than those in lean subjects. The levels of plasma NE, insulin, and leptin increased with weight gain in the 4 study groups. In the subjects with BP elevation, the increase in pulse rate and plasma NE was significantly greater than that in the subjects without BP elevation at both 6 and 12 months for each of the 4 study groups, although the increase in BMI was similar between the subjects with and without BP elevation. In obese but not lean subjects, whether normotensive or hypertensive, the increases in plasma insulin and plasma leptin with weight gain were greater in the subjects with accompanying BP elevation compared with the subjects without BP elevation. On the other hand, at 6 months in lean subjects, the increase in plasma insulin with weight gain in the subjects with BP elevation was actually lower than that in the subjects without BP elevation. These results suggest that weight gain-induced sympathetic overactivity is more tightly linked to weight gain-induced BP elevation than the changes in plasma insulin and leptin that also accompany weight gain. It is probable that sympathetic nervous activation with weight gain is a major mechanism of blood pressure elevation. Hyperinsulinemia and hyperleptinemia may be ancillary factors that contribute to sympathetic nervous stimulation with weight gain.

Retroperitoneal laparoscopic lateral approach to the lumbar spine: a new approach, technique, and clinical trial

A retroperitoneal laparoscopic (retroperitoneoscopic) lateral approach to achieve decompression for a far lateral disk lesion in the lumbar spine or to remove a paravertebral neurinoma without disrupting the facet is described. The operating space is maintained using a powered mechanical lift and a flat inflatable retractor mainly to make a longitudinal separation between the psoas major and the quadratus lumborum. This technique has been performed successfully in 22 cases using retroperitoneoscopy. The best indications of this new procedure are lateral disk herniation at the L5-S1 level or around the conus medullaris at the L1-L2 level. The described procedure provides adequate exposure necessary for extraforaminal exploration, discectomy, and nerve root decompression, and it is sufficient for treating extreme lateral lumbar herniation localized to the L1-S1 level and spinal nerve root tumors.

A linkage map of 243 DNA markers in an intercross of Göttingen miniature and Meishan pigs

A resource family of pigs has been constructed by using a boar of Göttingen miniature pig and two sows of Meishan pig as parents. In the construction of the family, two F1 males and 18 F1 females were intercrossed to generate 143 F2 offspring. The members of the family were genotyped using 243 genetic markers including 26 markers developed in our laboratory in order to generate a linkage map of markers for use in detecting quantitative trait loci (QTLs) in the family. The markers consisted of 237 microsatellites, five PRE-1 markers, and one RFLP marker. The linkage map was revealed to cover all 18 autosomes and the X chromosome; and the total length of the sex-averaged linkage map was calculated to be 2561.9 CM. Four out of the 26 markers developed in our laboratory exended the current linkage map at the termini of chromosomes 1p, 5p, 11p, and Xq. The linkage maps of all the chromosomes except for chromosome 1 were found to be longer in females than in males. Concerning chromosome 1, the length of the linkage map showed no difference between females and males, which was attributed to low recombination rates between markers localized in the centromeric region in females. The average ratio of female-to-male recombination was calculated to be 1.55.

The Ortho-to-Para Ratio of Ammonia in the L1157 Outflow

We have measured the ortho-to-para ratio of ammonia in the blueshifted gas of the L1157 outflow by observing the six metastable inversion lines from &parl0;J,K&parr0;=&parl0;1,1&parr0; to (6, 6). The highly excited (5, 5) and (6, 6) lines were first detected in the low-mass star-forming regions. The rotational temperature derived from the ratio of four transition lines from (3, 3) to (6, 6) is 130-140 K, suggesting that the blueshifted gas is heated by a factor of approximately 10 as compared to the quiescent gas. The ortho-to-para ratio of the NH3 molecules in the blueshifted gas is estimated to be 1.3-1.7, which is higher than the statistical equilibrium value. This ratio provides us with evidence that the NH3 molecules have been evaporated from dust grains with the formation temperature between 18 and 25 K. It is most likely that the NH3 molecules on dust grains have been released into the gas phase through the passage of strong shock waves produced by the outflow. Such a scenario is supported by the fact that the ammonia abundance in the blueshifted gas is enhanced by a factor of approximately 5 with respect to the dense quiescent gas.

Amalgam allergy associated with exacerbation of aspirin-intolerant asthma

BACKGROUND

Aspirin-intolerant asthma can be induced not only by acidic analgesics (including acetylsalicylic acid), which effectively inhibit cyclo-oxygenase, but also by cross-reactivity with paraben, and other chemical additives.

OBJECTIVE

We examined whether amalgam allergy is involved in the pathogenesis of a aspirin-intolerant asthma.

METHODS

We present the first case of aspirin-intolerant asthma that improved after the removal of dental amalgam. In addition, we performed both the methacholine provocation testing and sulpyrine provocation testing before and after the removal of dental amalgam.

RESULTS

In addition, the methacholine concentration causing a 20% fall in FEV1 in provocation tests rose significantly, though hypersensitivity to analgesics evaluated with sulpyrine provocation testing did not decrease. These results suggest that amalgam sensitization is involved in bronchial hyperresponsiveness in aspirin-intolerant asthma.

CONCLUSION

Sensitivity to amalgam may cause exacerbation of aspirin-intolerant asthma in some patients. To the best of our knowledge, this is the first case report of amalgam allergy associated with aspirin-intolerant asthma.

Factors related to impairment of activities of daily living

OBJECTIVE

We examined the factors related to the impairment of activities of daily living (ADL).

METHODS

ADL was evaluated by using ADL-20, which consists of 20 items from 4 major categories of activities; mobility, self-care, instrumental, and communication. The patients' gender, birth date, clinical diagnosis, past history, life styles, physical findings, laboratory data, and details of therapy were also recorded. Patients A total of 1,163 outpatients aged 50 years or older were included. Data from 1,093 patients were analyzed.

RESULTS

We divided the subjects into two groups; Group I having full marks of ADL-20 (n=582) and group II exhibiting an impairment of ADL (n=511). Multiple logistic analysis revealed that in both sexes age and stroke were common independent factors related to the impairment of ADL. Other factors associated with impairment of ADL were smoking in men and presence of proteinuria in women. The presence of hyperlipidemia was associated with preservation of the ADL in women.

CONCLUSION

The results demonstrated significant associations of smoking in men and the presence of proteinuria in women with the impairment of ADL in elderly Japanese outpatients. There appears to be a sex difference in the risk factors of impairment of ADL.

Angiotensinogen gene-activating elements regulate blood pressure in the brain

Although the angiotensinogen gene is a possible candidate as a determinant of hypertension, the molecular mechanisms of tissue angiotensinogen gene regulation have yet to be clarified. We identified essential transcription regulators of angiotensinogen production in the central nervous system using synthetic double-stranded oligodeoxynucleotides (ODNs) as "decoy" cis elements to block the binding of nuclear factors to promoter regions of the targeted gene. Using a gel mobility shift assay, angiotensinogen gene-activating element (AGE) 2 binding protein was detected in the brain nuclear extracts of both spontaneously hypertensive rats (SHRs) and normotensive Wistar Kyoto rats (WKYs). Importantly, the binding activity of AGE 2 and angiotensinogen mRNA level were significantly higher in the brain of SHRs than in that of WKYs. Using the decoy approach, we demonstrated a significant decrease in the blood pressure of SHRs by transfection of AGE 2 decoy, but not mismatched, ODNs into the lateral cerebroventricle, accompanied by a significant decrease in brain angiotensinogen concentration and mRNA, and angiotensin II level. That these effects, demonstrated herein, are due to central effects is confirmed by the fact that no changes in circulating levels of angiotensinogen or angiotensin II concentrations were observed. Notably, AGE 2 decoy ODNs did not decrease the blood pressure of WKYs. We conclude that the abnormal expression of AGE 2 binding protein in the central nervous system plays a crucial role in high blood pressure of a genetically hypertensive rat model.

[Multicenter prospective survey of prognosis of hypertensive elderly outpatient under antihypertensive treatment--morbidity and mortality of cardiovascular diseases and cancer]

Although calcium-channel blockers and angiotensin-I-converting enzyme inhibitors are often used for treatment of hypertension in the elderly in Japan compared to those in the United States and in European countries, there have been few investigations on the prognosis of the elderly receiving these antihypertensive treatments. The Research Group for "Guidelines on the Treatment of Hypertension in the Elderly" collaborated with the Comprehensive Research Projects on Aging and Health group of the Ministry of Health and Welfare of Japan in performing a 3-year survey on the outcome of 700 hypertensive elderly outpatients (> or = 60 years) receiving treatment of antihypertensive drugs. Antihypertensive drugs including dihydropyridine-type calcium channel blockers, beta blockers, angiotensin-I-converting enzyme inhibitors, diltiazem, diuretics and old-type antihypertensives (hydralazine, budralazine, and centrally acting drugs such as clonidine, methyldopa and guanabenz) were administered to 71.3%, 30.4%, 26.2%, 14.0%, 8.6%, and 6.4% of the 642 elderly patients surveyed for three years, at the time of registration, respectively. Morbidity and mortality rates of total cerebro-cardiovascular diseases, stroke, and heart diseases, were 27.6 and 7.81/1,000 patient-years, 15.1 and 3.6/1,000 patient-years, 10.4 and 4.2/1,000 patient-years, respectively. These results were similar or even better than those of megatrials of antihypertensive treatments for elderly patients in Europe and United States. After adjustment for potential confounding factors, multiple logistic analysis revealed that a past history of ischemic heart disease, use of the old-type antihypertensive drugs, male gender, and diastolic high blood pressure were independent risk factors for the morbidity of cerebro-cardiovascular diseases taking the group of non-cerebro-cardiovascular disease as the reference group. We also identified 22 cases of newly occurred malignancies including 7 fatal cases. However, none of the antihypertensives was significantly related to the occurrence of malignancies. These results lead support to the tendencies in the use of antihypertensive drugs in Japan.

Effects of NTE-122, an acyl-CoA:cholesterol acyltransferase inhibitor, on cholesterol esterification and lipid secretion from CaCo-2 cells, and cholesterol absorption in rats

The effect of NTE-122 (trans-1,4-bis[[1-cyclohexyl-3-(4-dimethylamino phenyl)ureido]methyl]cyclohexane), an acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, on cholesterol absorption was investigated. NTE-122 inhibited whole-cell ACAT activity in CaCo-2 cells, a human intestinal cell line, with an IC50 value of 4.7 nM. In CaCo-2 cells cultured on a membrane filter, NTE-122 pronouncedly inhibited the basolateral secretion of newly synthesized cholesteryl esters, and significantly reduced the basolateral secretion of newly synthesized triglycerides without influencing the cellular triglyceride synthesis. Furthermore, NTE-122 (1 mg/kg, p.o.) inhibited [14C]cholesterol absorption in rats. These results suggest that NTE-122 is capable of exhibiting anti-hyperlipidemic effects by reducing the absorption of dietary cholesterol.

[Quality of life in the pharmacologically treated elderly patients]

The quality of life has been shown to decline with advancing age, being affected by health status, physical symptoms due to multiple chronic diseases, and the level of remaining activities of daily living of the elderly. In the pharmacologic treatment of the elderly, attention must be paid to such backgrounds and adverse side effects of drugs must be considered in order to maintain the QOL of the elderly which has already been jeopardized. Therefore, prescriptions should be consist of drugs concerning the effects on the QOL have been established. Physicians and medical personnels treating or caring for the elderly should take into account the balance between the quantity and the quality of their remaining life.

Effect of propranolol on central neurotransmitter release in Wistar rats analysed by brain microdialysis

1. The effect of propranolol on amino acid neurotransmitter release in the rostral ventrolateral medulla (RVLM) was examined in urethane-anaesthetized male Wistar rats. 2. Amino acids released in the RVLM in response to intravenous administration of propranolol (0.4 mg/kg per min; n = 6) or nitroglycerin (0.02 mg/kg per min; n = 5) were determined by the brain microdialysis method. 3. Amino acids in dialysates were analysed by high-performance liquid chromatography and were quantified by ultraviolet absorbance. 4. Administration of both intravenous propranolol and nitroglycerin significantly decreased arterial blood pressure. Heart rate was decreased only by propranolol. 5. The reduction in arterial blood pressure produced by intravenous propranolol was accompanied by a decrease in the release of the excitatory amino acid glutamate in the RVLM. 6. The reduction in arterial blood pressure following intravenous nitroglycerin was not accompanied by a release of glutamate. 7. There were no significant changes in the levels of other amino acids (glycine, taurine, GABA) following either propranolol or nitroglycerin. 8. The decrease in glutamate release in the RVLM may account, in part, for the central depressor mechanism of propranolol.

Molecular analysis of methylmalonyl-CoA mutase deficiency: identification of three missense mutations in mut0 patients

Genetic defects in the methylmalonyl-CoA mutase (MCM) gene cause methylmalonic acidemia (MMA). Only three mutations have been reported among Oriental patients to date. We studied fibroblast cell lines established from three Japanese patients with MCM deficiency. Enzymatic study showed that these patients had the muttype of MMA. Nucleotide sequencing of MCM cDNAs identified three missense mutations: a T to A change at nucleotide position 2082, which results in an amino acid substitution of Glu669 for valine (V669E); a T to A change at position 1179 with the corresponding amino acid substitution of Asp368 for valine (V368D); and a G to A change at position 1182 with the corresponding amino acid substitution of His369 for arginine (R369H). Each of the three missense mutations abolished MCM activity according to a transient expression study. Alignment of these mutations with a recently reported homology model of human MCM allowed us to speculate on the effect of these nonconservative amino acid substitutions on MCM activity: V368D and R369H affected residues in the beta/alpha-(TIM-) barrel domain, on one of the two alpha-helices that form the dimer interface, while V669E altered a residue in the adenosylcobalamin-binding domain in the C terminus.

Primary cutaneous T-cell lymphoma involving the cheek: an infant case with a unique clinicopathologic feature

We report a clinicopathologic feature of primary cutaneous T-cell lymphoma (CTCL) in a five-year-old boy with increasing swelling of his cheek since two years of age. Histologically, an infiltrate of atypical lymphoid cells with mature T-cell phenotype and clonality was prominent from the dermis to the subcutaneous tissue of the cheek. Although little effect was seen with aggressive multidrug-combined chemotherapy, therapy with interferon-alpha and steroids achieved a prolonged remission. This patient may provide important clues to understanding the clinicopathologic feature of rare primary CTCL in young children.

Airway responsiveness to acetylcholine in congenitally bronchial-hypersensitive (BHS) and bronchial-hyposensitive (BHR) guinea pigs in vivo and in vitro

The characteristics of airway responsiveness to acetylcholine (ACh) in congenitally bronchial-hypersensitive (BHS) and bronchial-hyposensitive (BHR) guinea pigs were clarified in vivo and in vitro. We measured the change in ventilatory mechanics in response to ACh inhalation by means of the bodyplethysmograph and the contractile responses of isolated trachea to ACh and carbachol (CCh). Further, muscarinic receptor subtypes involved these responses were identified. The basal values for ventilatory mechanics in BHS were not significantly different from those in BHR. Respiratory resistance to ACh was progressively increased in a time- and dose-dependent manner in BHS. The contractile responses of tracheal smooth muscle to ACh in BHS were significantly greater than those in BHR, but CCh-induced responses in BHS and BHR were similar. ACh- and CCh-induced contractions were mediated via M3 receptors. These results suggested that the falling-down of BHS in response to ACh inhalation was caused by the strong constriction of the airway and the reduction in ventilation. Moreover, the airway hyperresponsiveness to ACh in BHS might be partly dependent on the change in acetylcholinesterase activity.

Familial hypertension, insulin, sympathetic activity, and blood pressure elevation

This study evaluated the effects of a positive family history of hypertension (FH+) on the contributions of sympathetic nervous system (SNS) activity and insulin to blood pressure elevation (BPE). The study design was longitudinal and evaluated BP, body mass index (BMI), and fasting plasma insulin and norepinephrine (NE) levels for 10 years in 557 young, nonobese Japanese men who were normotensive at entry. FH+ was defined as hypertension in first-degree relatives as verified by historical records or direct determination. BPE was defined as a > or = 10% rise in systolic and diastolic BP over entry levels during the 10-year period. In the total group FH+ was noted in 16%, and BPE occurred in 18% of normotensive subjects. When evaluated by FH, the prevalence of BPE was 33% in FH+ compared with 16% in FH- (P<0.05). BP levels were greater both at entry and at year 10 in the FH+ group. The absolute increment in plasma NE over 10 years was greater in the BPE group than in those without BPE (P<0.01). Of note, the rise in plasma NE levels in BPE individuals was identical in FH+ and FH- subjects. Plasma insulin increments were also greater in normotensive subjects with BPE than in normotensive subjects without BPE. However, compared with NE, development of hyperinsulinemia was more pronounced in the FH+ subjects. The results indicate that SNS hyperactivity may be a less genetically determined predictor of hypertension than is hyperinsulinemia. Because SNS changes in this initially normotensive population appeared more closely related to the development of hypertension than to hyperinsulinemia, environmental rather than genetic factors may be the main determinant of early BPE in nonobese normotensive subjects.

The surgical treatment of lung lacerations and major bronchial disruptions caused by blunt thoracic trauma

The records of 16 patients who suffered blunt thoracic trauma, causing lung lacerations in 13, bronchial disruptions in 2, and lung laceration with bronchial disruption in 1, were reviewed to investigate the correlations between clinical factors and prognosis. The causes of these injuries included 14 traffic accidents and 2 construction-related accidents, and the indications for surgery were massive bleeding in 12 patients, massive air leakage in 2, both in 1, and lung abscess in 1. Of the 16 patients, 11 (68.8%) underwent thoracotomy less than 4 h after admission, 3 (18.8%) underwent thoracotomy 4 to 24 h after admission, and 2 (12.5%) underwent thoracotomy 24 h or later after admission. The operative techniques included 1 pneumonectomy, 5 lobectomies, 2 bronchoplasties, and 8 minor repairs. The mortality rate was 43.7%, which included six early deaths occurring within 72 h of the trauma, and one late death. While major bronchial disruption is usually associated with a good prognosis, univariate and multivariate analyses demonstrated that intrapleural bleeding of 300 ml/h or more from time of trauma to chest tube drainage was significantly correlated with a poor prognosis. Moreover, an injury severity score (ISS) of 36 or more showed a trend toward a correlation with poor prognosis in patients with lung lacerations. Prompt thoracotomy will decrease mortality rate of patients suffering lung lacerations resulting in intrapleural bleeding of more than 300 ml/h.

p53 and Bcl-2 expression in pneumoconiosis-related pre-cancerous lesions and lung cancers: frequent and preferential p53 expression in pneumoconiotic bronchiolar dysplasias

To explore the mechanism by which lung cancers excessively arise from pneumoconiosis, we determined the altered expression of p53 and Bcl-2 by immunohistochemistry (IHC) in lung cancers, dysplasias and non-cancerous pulmonary epithelia in pneumoconiotics in comparison with those from non-pneumoconiotic patients. We examined p53 expression in squamous cell carcinomas (SCCs) and dysplasias separately in the central and peripheral zones of bronchial trees, based on observations that SCCs from pneumoconiotic patients occurr more frequently in peripheral epithelia than those from non-pneumoconiotic patients (55 of 72 SCCs with pneumoconiosis vs. 33 of 72 SCCs without pneumoconiosis). Forty-one of 72 patients with pneumoconiosis-related lung cancers had altered p53 expression, which was comparable to the positivity of p53 expression in lung cancers without pneumoconiosis. p53 expression was observed significantly more frequently in bronchiolar dysplasias with pneumoconiosis than in those from non-pneumoconiotic patients (13 of 23 vs. 4 of 22), while p53 expression was found in bronchial dysplasias with pneumoconiosis as frequently as those without pneumoconiosis. Moreover, in patients with pneumoconiosis, bronchiolar dysplasias exhibited p53 expression more frequently than bronchial dysplasias (13 of 23 vs. 4 of 19). When comparison was restricted to bronchiolar dysplasias from patients without lung cancer, p53 expression had a strikingly higher frequency in the dysplasias with pneumoconiosis than in those from non-pneumoconiotic patients (8 of 15 vs. 0 of 14). Bcl-2 occasionally was expressed in squamous metaplasias and basal cell hyperplasias, in contrast to p53, for which immunostaining was negative in these lesions. Altogether, our results show that pre-cancerous and/or cancerous targets in pneumoconiosis may be distributed over a more peripheral zone than those in patients without pneumoconiosis.

Central amino acids mediate cardiovascular response to angiotensin II in the rat

To elucidate the role of the rostral ventrolateral medulla (RVLM) in cardiovascular control through the release of central amino acid neurotransmitters, experiments were performed in Sprague-Dawley (normotensive) rats and spontaneously hypertensive rats (SHR) anesthetized with urethane by using microdialysis sampling from the RVLM for determination of amino acid neurotransmitters. The baseline release of the excitatory amino acid neurotransmitter, glutamate (GLU) from the RVLM in SHR was higher and those of the inhibitory amino acid neurotransmitters, glycine (GLY), taurine (TAU), and gamma-aminobutyric acid (GABA), were lower than in normotensive rats. Microinjection of angiotensin II (ANG II) into the RVLM caused a dose-dependent increase in mean arterial pressure (MAP) and heart rate (HR), accompanied by increased release of GLU in the RVLM. In contrast, microinjection of the ANG II type 1 receptor (AT1) antagonist CV 11974 into the RVLM reduced MAP and HR, accompanied by increased release of GLY, TAU and GABA. These changes in MAP and HR after administration of ANG II or AT1 antagonist were partially blocked by the use of the corresponding antagonist of each amino acid neurotransmitter. Furthermore, these effects were more prominently seen in SHR than in normotensive rats. These results suggest that the release of amino acid neurotransmitters mediate the cardiovascular effects of the angiotensin system in the RVLM, which may be involved in the generation of hypertension in SHR.

Histamine-induced airway contraction in congenitally bronchial-hypersensitive (BHS) and bronchial-hyposensitive (BHR) guinea pigs

Airway hyper-responsiveness is known as an important pathogenesis of asthma. In the present study, the airway responsiveness to aerosolized and injected histamine in congenitally bronchial-hypersensitive (BHS) and bronchial-hyposensitive (BHR) guinea pigs was investigated. In addition, the role of the vagal reflex in histamine-induced airway contraction was evaluated by vagal blocking with atropine inhalation or bilateral vagotomy. A significantly higher bronchoconstrictive reaction, i.e., a decrease in tidal volume (VT) and an increase in respiratory resistance (Rrs), to histamine-inhalation was observed in BHS than in BHR. A noticeably lower reduction in VT was noted after atropine pretreatment for both BHS and BHR, whereas an increase in Rrs was inhibited only in BHS. The intravenous injection of histamine caused a noticeable bronchoconstrictive reaction in both BHS and BHR with a dose-dependent relationship, but no significant differences were observed and the bilateral vagotomy failed to induce any difference between the two animal groups. These results demonstrated that the airway responsiveness to histamine is considerably different in BHS from that in BHR, but the difference is largely dependent on the route of administration of histamine. The important role of the vagal reflex on the elicitation of airway contraction was elucidated in both animal groups, and it appeared that the BHS possessed relatively higher dependency on the vagal reflex mechanism than the BHR.