Search PubMed⌕ Search

Biomedical subjects

K Katahira

Publications and source records attributed to K Katahira.

At least 37 records · Page 2Linked to original sources
PubMed1996

[Measurement of the common carotid arterial flow during parabolic flight in the anesthetized rat].

To measure the blood flow of a common carotid artery (CCA) during parabolic flight in the rat, we developed an animal double hold box (ADHB) made of styrene expanded form for the anesthetized rat to keep the animal at a proper posture in an aircaft. Twelve anesthetized rats weighing 291-342 g were surgically operated to mount a ultrasound flowmeter probe (1 mm size,1RS:Transonic Systems Inc.) around the right CCA and to insert a catheter into the right axillar artery for blood pressure measurement. These animals were held comfortably in ADHBs which were placed on the rack installed in the aircraft (MU-300). A total of 27 parabolic flights was performed and the blood flow was measured accurately in 9 rats. This special animal holding facility is useful for various types of animal experiments in an aircraft.

Animals↗
PubMed1996

Excitatory response of rabbit myometrium to nitric oxide in vitro.

Nitric oxide (NO) at high concentration (approx. 33 microM) produced a marked excitation: increase of tension development or increase in amplitude of spontaneous contraction, in 7 out of 8 rabbit nonpregnant myometrial strips. One case produced an inhibition: disappearance of spontaneous contraction. A latent period of several sec usually preceded the excitation. The response of the myometrium to NO approx. 33 microM associated with remarkable increase in tissue cyclic GMP levels. NO approx. 33 microM reduced an inhibition, in 1 out of 3 myometrial strips taken from ovariectomized rabbits. Two cases produced an excitatory. A precursor of NO, L-Arginine 100 microM or an inhibitor of NO synthase, NG-nitro-L-arginine 100 microM also produced a transient weak excitatory response. On the contrary, 8-bromo-cyclic GMP 100 microM produced an inhibition. The excitatory response to NO 33 microM was almost unaffected by pretreatment with indomethacin 10 microM, whereas the spontaneous motility was remarkably depressed. The contractile response of the isolated rabbit myometrium to electrical field stimulation was almost unaffected by the pretreatment with L-arginine 100 microM or NG-nitro-L-arginine 100 microM. The present findings may indicate that NO has inhibitory and excitatory components on the mechanical activity of the rabbit isolated myometrium.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1995

Evidence suggesting that the odortypes of pregnant women are a compound of maternal and fetal odortypes.

Odortypes--namely, body odors that distinguish one individual from another on the basis of genetic polymorphism at the major histocompatibility complex and other loci--are a fundamental element in the social life and reproductive behavior of the mouse, including familial imprinting, mate choice, and control of early pregnancy. Odortypes are strongly represented in urine. During mouse pregnancy, an outcrossed mother's urine acquires fetal major histocompatibility complex odortypes of paternal origin, an observation that we took as the focus of a search for odortypes in humans, using a fully automated computer-programmed olfactometer in which trained rats are known to distinguish precisely the odortypes of another species. Five women provided urine samples before and after birth, which in each case appropriately trained rats were found to distinguish in the olfactometer. Whether this olfactory distinction of mothers' urine before and after birth reflects in part the odortype and hence genotype of the fetus, and not just the state of pregnancy per se, was tested in a second study in which each mother's postpartum urine was mixed either with urine from her own infant or with urine of a different, same-aged infant. Responses of trained rats were more positive with respect to the former (congruous) mixtures than to the latter (incongruous) mixtures, implying that, as in the mouse, human fetal odortypes of paternal genomic origin are represented in the odortype of the mother, doubtless by circulatory transfer of the pertinent odorants.

Animals↗
PubMed1995

Amino acids in the medulla oblongata contribute to baroreflex modulation by angiotensin II.

We investigated the underlying mechanisms of baroreflex alteration produced by intravenous angiotensin II (ANG II) by monitoring the release of amino acids from the rostral ventrolateral medulla (VLM) using a brain microdialysis technique. Reflex changes in heart rate were elicited by bolus intravenous injection of phenylephrine (2-40 micrograms/kg) before and 120 min after the initiation of administration of a subpressor dose of ANG II (5.4 pmol/kg/min) or vehicle. The slope of the regression line obtained from changes in mean arterial pressure and heart rate elicited by phenylephrine was used as an index of baroreceptor reflex sensitivity. ANG II administration for 120 min significantly attenuated the baroreflex sensitivity (from -0.59 +/- 0.10 to -0.30 +/- 0.08 bpm/mmHg). This attenuation was accompanied with an increase in the release of glutamate and glycine from the VLM (+40% and +20%, respectively) at 120 min. Glycine perfusion into this area resulted in an attenuation of baroreflex sensitivity with a magnitude similar to that obtained with infusion of a subpressor dose of ANG II, whereas glutamate perfusion caused a resetting of baroreflex. These results suggest that glycine and glutamate are involved in cardiovascular regulation in the VLM. Furthermore, the augmented releases of these amino acids may account for the underlying mechanism of ANG II-induced attenuation of baroreflex function.

Amino Acids↗
PubMed1994

Differential control of vascular tone and heart rate by different amino acid neurotransmitters in the rostral ventrolateral medulla of the rat.

1. To test the hypothesis that a central mechanism may play a role in the minimal reflex tachycardia noted in response to peripheral converting enzyme inhibition, we compared the effects of intravenous (i.v.) ceronapril (CER) with nitroglycerin (NTG) on neurotransmitter release in the rostral ventrolateral medulla (RVLM), using an in vivo microdialysis method in pentobarbital anaesthetized rats. 2. CER (0.1 mg/kg, i.v.) caused a progressive decrease in glutamate (GLU) release (CER 65 +/- 7% vs NTG 83 +/- 3% of each baseline at 140 min, P < 0.05) and attenuated the increase in glycine (GLY) release (CER 100 +/- 8% vs NTG 122 +/- 9%, P < 0.05). 3. Prevention of blood pressure reduction due to i.v. CER by concomitant infusion of a subpressor dose of angiotensin II (AII) attenuated the progressive reduction of GLU release (87 +/- 4%, P < 0.05 compared with NTG group), whereas GLY release was not affected (106 +/- 5%, NS compared with NTG group). 4. Perfusion of GLU into this area at approximately physiological concentrations resulted in a sustained tachycardia with an attenuation of the depressor effect of i.v. CER and perfusion of GLY solely lowered blood pressure. 5. These results demonstrate that i.v. converting enzyme inhibitor reduces the release of GLU in the RVLM, which was specifically caused by reducing circulating AII, without any effect on GLY release, thus resulting in the reduction of blood pressure with minimal effect on the heart rate.

Anesthesia↗
PubMed1993

Reference values for organ weight, hematology and serum chemistry in the female ferret (Mustela putrius furo).

Organ Weight, hematologic and blood chemistry values were determined to establish reference values in the female ferret. Organ weight per kg body weight was calculated for various organs. Body surface area (BSA) was also determined by the direct method, and K values (constant) were calculated. The K value was 3.48 in the Dubois and Dubois equation, and 9.69 in the Meeh-Rubner equation. Blood samples were used to record 10 hematologic and 57 serum (plasma) chemistry values, and 7 immunological parameters. Among hematologic values, values whose coefficient of variation (cv) exceeded 30% were RBC, WBC and PLT. In blood chemistry, the CV of gamma-G, UA, ZTT, GPT, gamma-GTP, MAO, ALD and IgG exceeded 30%. In the total amino acid analysis, only the CV of TAU exceeded 30%. Electrophoretograms of amylase and CPK isozyme were quite different from those of humans. Although 1-MEHIS, 3-MEHIS and CAR have not been detected or are present in trace amounts in human plasma, concrete values were detected in female ferret plasma. Hematologic and serum chemistry values were in general agreement with normal values seen in cats and dogs. However, the alpha 1-G percentage, and ALP and amylase activities were lower than the corresponding values in cats and dogs. The RBC count, RET-C percentage and LDH activities were higher than in cats and dogs. Since there have been no comprehensive articles on reference values for the female ferret, the present report contributes to studies that involve this animal as an experimental model.

Alanine Transaminase↗
PubMed1993

Indirect measurement for body surface area of cotton rats.

The body surface areas (BSAs) of 42 cotton rats (21 females weighing 29.08 to 169.60 g, and 21 males weighing 18.93 to 168.03 g) were measured. From these areas and body weights (BW), the equation, BSA (cm2) = 47.66 + 2.476 x BW (g) -0.006 x BW (g)2, was derived. To verify the applicability of the equation, the BSAs of another 19 animals (12 females weighing 29.08 to 169.60 g, and 7 males weighing 19.27 to 167.32 g) were calculated and the values compared with the measured BSAs. The correlation between calculated and measured BSAs was significant (r = 0.995, P < 0.01). Therefore, this equation can be used to calculate cotton rat BSA.

Animals↗
PubMed1993

Hematological standard values in the cotton rat (Sigmodon hispidus).

The purpose of this study is to establish reference data on several hematological parameters in the cotton rat. Eight hematological values were measured in 28 males and 29 females at 16 to 18 weeks of age. Females showed significantly lower RBC, Ht and MCV values than males. Female Hb and PLT values tended to be lower than male values, although differences did not reach a conventional level of significance. WBC and PLT values varied widely in both sexes.

Animals↗
PubMed1992

Spectral change in heart rate variability in response to mental arithmetic before and after the beta-adrenoceptor blocker, carteolol.

Spectral analysis of heart rate fluctuation was evaluated before and after administration of carteolol, a non-selective beta-adrenoceptor-blocker, to investigate the neural regulatory mechanisms underlying the haemodynamic changes induced by mental stress. Mental stress increased blood pressure and heart rate, with an increased low frequency band, and low frequency/high frequency ratio of the power spectral analysis which are indices of sympathetic activity. Carteolol did not change basal and pre-mental stress measurements of blood pressure, heart rate and spectral density. However, carteolol altered the response to mental stress with a decrease in spectral density of the low frequency band and low frequency/high frequency ratio, and an increase in the high frequency component. These results confirm that mental stress elevates blood pressure by activating the sympathetic nervous system, and suggest that blockade of the beta-adrenoceptor attenuates the pressor response by preventing the autonomic responses to mental stress.

Blood Pressure↗
PubMed1991

Comparative study of the effects of three angiotensin converting enzyme inhibitors on the cough reflex.

To compare the effects of three different angiotensin converting enzyme (ACE) inhibitors on the cough reflex, capsaicin and citric acid challenge tests were done in normal subjects and hypertensive patients before and after administration of delapril, captopril, or enalapril. Two groups of 7 normal subjects (single dose study: 15 mg delapril v 18.75 mg captopril or 2.5 mg enalapril) and a group of 6 mildly hypertensive patients (1 week study: cross-over administration of 30 mg/day delapril, 37.5 mg/day captopril, or 5 mg/day enalapril) were studied. Another group of 6 patients with essential hypertension was treated with three ACE inhibitors for 4 weeks in a randomized order, with a 2 week washout period between active therapies. Aerosols of 1 mumol/L and 3 mumol/L capsaicin and 0.68% citric acid in 0.9% NaCl were generated by an ultrasonic nebulizer, and the frequency of cough was counted during inhalation. Delapril treatment resulted in substantially fewer patients with a significant increase (greater than or equal to 4 coughs during treatment than during the control period) in the frequency of cough than did captopril treatment. In the 1 and 4 week studies, enalapril and captopril had substantially more occurrences of significantly increased capsaicin-induced cough than did delapril. These results indicate that delapril has the least cough stimulatory effect among these ACE inhibitors, which may be clinically beneficial.

Administration, Inhalation↗
PubMed1991

Converting enzyme inhibitors regressed cardiac hypertrophy and reduced tissue angiotensin II in spontaneously hypertensive rats.

To examine the role of the tissue renin-angiotensin system in left ventricular hypertrophy, converting enzyme inhibitors were administered orally to 12-week-old male spontaneously hypertensive rats (SHR) for 4 weeks, and cardiac tissue angiotensin II was measured. Treatment with enalapril (10 mg/kg per day) and trandolapril (1 mg/kg per day) lowered systolic blood pressure, left ventricular weight and left ventricular angiotensin II content. Plasma angiotensin II concentration was increased by the treatment with enalapril whereas trandolapril did not cause any change. There was significantly positive correlation between left ventricular weight and angiotensin II content. Because angiotensin II promotes cell proliferation, these results suggest that cardiac tissue angiotensin II, rather than circulating angiotensin II, may account for the pathophysiology of left ventricular hypertrophy in SHR.

Angiotensin II↗
PubMed1991

Effect of long-term treatment with an angiotensin-converting enzyme inhibitor on the renin-angiotensin system in spontaneously hypertensive rats.

1. To obtain information on regulation of the brain renin-angiotensin system, the effect of long-term administration of angiotensin-converting enzyme (ACE) inhibitor on brain renin and angiotensinogen mRNA was studied. 2. Spirapril (3 mg/kg) was orally administered daily for 8 weeks to spontaneously hypertensive rats (SHR) from 12 weeks after birth. Renin and angiotensinogen mRNA in the brain and kidney were then quantitated by Northern blot analyses with [32P]-labelled rat renin and angiotensinogen cDNA as hybridization probes. Plasma renin activity (PRA), angiotensin II (AII) concentration, plasma ACE activity and brain tissue ACE activity were also measured. 3. Compared with the control group, the Spirapril-treated group had significantly lower blood pressure (P less than 0.01), significantly higher PRA (P less than 0.01), a not significantly different plasma AII concentration, and lower plasma and brain ACE activities (P less than 0.01). Interestingly, the brain renin and angiotensinogen mRNA levels of the two groups were similar, but the renal renin mRNA level was significantly higher in the Spirapril-treated group (P less than 0.01). 4. These results indicate that the mRNA levels of brain renin and angiotensinogen were not affected by chronic ACE inhibition in the circulation and suggest that AII in the brain might not be affected by systemic ACE inhibition.

Actins↗
PubMed1991

Importance of the sympathetic nervous system in blood pressure elevation by subpressor intraventricular NaCl and angiotensin II in the rat.

The present study was performed to examine the effect of chemical sympathectomy with guanethidine on the BP change and humoral factors in rats which received continuous and concomitant infusion of i.c.v. hypertonic NaCl with i.v. Ang II, both at subpressor doses for 7 days. Male rats were divided into 3 groups which received the following infusions using an osmotic minipump at a rate of 1 microliter/min: Group 1 (n = 11), 0.15 M NaCl i.c.v. and Ang II (5.4 pmol/kg/min) i.v.; Group 2 (n = 9), 0.8 M NaCl i.c.v. and Ang II i.v.; Group 3 (n = 5), 0.8 M NaCl i.c.v. and Ang II i.v. with daily i.p. injection of guanethidine (40 mg/kg). Significant increase in BP was observed only in Group 2 (from 103 +/- 3 mmHg to 132 +/- 5 mmHg on day 7, p less than 0.001). Addition of i.p. guanethidine to i.c.v. infusion of 0.8 M NaCl and the subpressor dose of Ang II completely prevented increase in the BP, suggesting that the presence of the intact sympathetic nervous system is necessary for the development of BP elevation in response to i.c.v. hypertonic NaCl plus i.v. Ang II. Thus, the sodium status in the central nervous system is important in the regulation of BP and is closely related to the activity of the sympathetic nervous system.

Angiotensin II↗
PubMed1990

Differential blood pressure responses to oral and central salt administration in two substrains of Dahl rats.

Studies were made on whether oral or intraventricular (icv) NaCl had different effects on the blood pressure (BP) of Dahl rats. Five groups of each strain of Dahl rats, salt-sensitive (S) and salt-resistant (R) rats, were given, respectively, a diet containing 0.3% and icv infusion of 0.15 mol/L NaCl (group 1, control group) or 0.8 mol/L NaCl (group 2), a diet containing 8% NaCl and icv infusion of 0.15 mol/L (group 3) or 0.8 mol/L NaCl (group 4) for 12 days, or an 8% NaCl diet and icv infusion of 5% glucose (group 5). The icv infusions were made into the third cerebral ventricle with an osmotic minipump. In the control group of S rats (group 1) the BP was 120 +/- 4 mm Hg, whereas the BP in groups 3, 4 and 5 were 154 +/- 4, 161 +/- 5 and 153 +/- 3 mm Hg, respectively, and that in group 2 was 142 +/- 3 mm Hg on day 12. In the R rat, group 2 and group 4 showed a significant increase in BP over that of the control group. Multivariate analysis (quantification I) of these data confirmed that the BP of S rats was more sensitive to oral salt loading and that of the R rat was more strongly influenced by central salt administration. These results indicate that the two substrains of Dahl rats show different BP responses to oral and central administrations of NaCl.

Animals↗
PubMed1990

Haemodynamic effect of endothelin, a novel potent vasoconstrictor in dogs.

1. The effects of endothelin (40 and 400 pmol/kg, intravenous (i.v.), a novel vasoconstrictor, on haemodynamics were evaluated in normal dogs and dogs treated with hexamethonium. 2. The lower dose of endothelin caused no significant changes in mean blood pressure (MBP), heart rate (HR), cardiac output (CO), or total peripheral resistance (TPR) in normal dogs. In dogs treated with hexamethonium MBP decreased transiently associated with decrease in TPR. 3. In both dogs, the higher dose of endothelin caused MBP increase with CO increase in an early phase, and with TPR increase in a later phase. In normal dogs, the CO decreased 60 min after endothelin, but in dogs treated with hexamethonium the decrease in CO was not significant. 4. Electrocardiograms showed ST changes and arrhythmias. 5. Thus, endothelin has dual effects on both the vasculature and the heart, its effect depending on its dose and the time after its administration: initial vasodilation followed by prolonged vasoconstriction, and cardiostimulation followed by cardiosuppression. The cardiosuppression appears to be mediated in part by a neural mechanism.

Animals↗
PubMed1990

Absence of nocturnal fall in blood pressure in elderly persons with Alzheimer-type dementia.

Circadian changes of the blood pressure and heart rate in elderly normotensive bedridden patients with severe dementia of the Alzheimer type (group D) were compared with those in elderly normotensive bedridden patients without dementia (group R), normotensive subjects with normal daily activity (group N), and hypertensive patients with normal daily activity (group H). In groups R, N, and H, the blood pressure increased in the afternoon and decreased at midnight; in group D, however, although it increased in the afternoon, it did not decrease at night. The circadian changes of the heart rate were similar in all four groups, showing maxima in the afternoon and minima at midnight. Thus, a specific alteration was found in the circadian rhythm of the blood pressure in patients with Alzheimer-type dementia.

Activities of Daily Living↗