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Biomedical subjects

T Ohhashi

Publications and source records attributed to T Ohhashi.

At least 109 records · Page 6Linked to original sources
PubMed1982

Contraction of arterial smooth muscle induced by magnesium ions.

Dose-response relationships for Mg2+ in a Mg2+-free bathing solution were obtained with isolated canine femoral arteries. At concentrations less than 5 mM, relaxant responses appeared in the preparations. In a concentration range of 10-20 mM, however, every one of the preparations invariably showed dose-dependent contractions. The relaxant and contractile responses were induced by the action of Mg2+ per se but not by the hyperosmolarity associated with the addition of Mg2+. Neither response was affected by the drugs that inhibited the actions of catecholamine, acetylcholine, serotonin, or histamine. The contractile response was kept unchanged in Ca2+-free Locke's solution and was almost independent of environmental calcium concentrations ranging from 2.2 to 8.2 mM. The contractile response was not affected under the influence of Ca antagonists, verapamil, or Mn2+. The presence of Ba2+ or Sr2+ enhanced the relaxant response and dose dependently suppressed the contractile response. The contractile response was still evoked in smooth muscles that were in the state of K+ contracture. These results suggest the possibility that the contractile action of Mg2+ was mediated by a release of intracellular Ca2+ or exerted directly on the contractile machinery of arterial smooth muscle.

Animals↗
PubMed1981

Conduction velocity of peristaltic waves in the in vivo ureter: application of a new diameter gauge.

The conduction velocity of peristaltic movements of the canine ureter was measured under anaesthesia with a new type of diameter gauge using an image sensor. The peristaltic velocity was 34.1 +/- 6.2 mm/sec in 10 experiments. Noradrenaline at a low dosage of 1 microgram/kg i.v. reduced the resting diameter, increased the conduction velocity to 47--56 mm/sec, and approximately doubled the frequency of contraction. The application of acetylcholine also caused an increase in both frequency and conduction velocity (42--46 mm/sec). A plot of the conduction velocity against the mean period of peristaltic contraction was hyperbolic in shape.

Acetylcholine↗
PubMed1981

The B region-associated antigens and MLR phenotypes in the Japanese inbred strains of rats.

Seven different alloantisera absorbed with red blood cells (RBC) from appropriate strains of rats detected a series of B cell alloantigenic specificities that could be divided into two groups, presumably coded for by at least two different closely-linked loci in the rat major histocompatibility complex (MHC), RT1. The one locus had two allele codes for a broad specificity and the other locus codes for a unique specificity that was found only in the restricted strains of rats that shared the same mixed lymphocyte reaction (MLR) phenotype. RBC-absorbed alloantisera were monitored against a panel of B cell fractions obtained from sixteen inbred strains. Two alloantisera, ACI anti-W and W anti-TO detected two broad specificities, into either of which all inbred strains tested were classified. Two broad RT1-B region-associated specificities were thus designated provisionally as Ba-1.1 and -1.2. Another five alloantisera detected four respective specificities which have a narrower strain distribution. Sixteen inbred strains were classified into one of five specificities detected by W and F344, F344 anti-SDJ, WKA anti-ACI, W anti-BUF and ACI anti-W absorbed with LEJ lymph node cells. Each specificity was designated provisionally as Ba-2.1, -2.2, -2.4, -2.6, -2.7, respectively. A complete association of Ba-2 specificities with MLR phenotype was observed. Antigenic specificities of Ba-2.2, -2.2 and -2.4 were all classified in a group of Ba-1.1 specificity, whereas Ba-2.6 and -2.7 specificities were associated with Ba-1.2 specificity. This relationship suggested a linkage disequilibrium between the two loci for the Ba antigens.

Animals↗
PubMed1981

Relaxation of bovine mesenteric lymphatics in response to transmural stimulation.

The responses of isolated quiescent segments of bovine mesenteric lymphatics to 10-s trains of pulses (50 V for 0.3 ms at 2 Hz) administered transmurally have been studied using various drugs. Each train of pulses consistently produced a brief contraction that was completely blocked by tetrodotoxin, alpha-adrenoceptor antagonists, bretylium, and guanethidine. Cocaine potentiated the contractions. Tyramine caused an increase in the basal tone, some spontaneous contractions, and an inhibition of contraction. The contraction was sometimes followed by a relaxation that could be of short duration or long lasting. Both types of relaxation were abolished by tetrodotoxin. Propranolol reduced both types of relaxation, causing more suppression of the short type. Bretylium completely blocked the short type of relaxation and slightly reduced the long-lasting type. Hexamethonium and atropine had no effect on any of the responses. These findings suggest that the contraction resulting from transmural stimulation is due to the action of excitatory postganglionic sympathetic nerves. It is concluded that both types of relaxation occur mainly in response to beta-adrenergic inhibitory stimulation. The possibility of nonadrenergic inhibitory innervation in bovine mesenteric lymphatics is also discussed.

Action Potentials↗
PubMed1981

[The mode of action of ATP on the isolated internal carotid artery (author's transl)].

Adenosine triphosphate (ATP) has been known to induce vasodilation in various vascular beds. Recently, we reported that ATP produced vasoconstrictions in isolated internal and external carotid arteries of dogs. In the present study, the mode of the ATP-induced vasoconstriction in the internal carotid artery was analysed from the physiological and pharmacological points of view. The results obtained were as follows: 1) ATP (5 X 10(-6) approximately 2 X 10(-4) M) caused dose-dependent vasoconstrictions in the internal carotid artery. 2) The ATP-induced vasoconstriction was not affected by pretreatment with phenoxybenzamine, propranolol, atropine, cyproheptadine, or tetrodotoxin. 3) Verapamil suppressed dose-dependently the contractile response. 4) ATP caused no vasoconstriction in a calcium-free Krebs solution containing Im M EGTA. 5) ATP produced no further vasoconstriction in the preparation which had been in a state of contracture in a high potassium Krebs solution. These results suggest that an increase of potential-dependent Ca++ influx into the arterial smooth muscle cells may play a major role in the ATP-induced vasoconstriction.

Adenosine Triphosphate↗
PubMed1980

A camera-type diameter gauge applicable to small blood and lymph vessels.

A camera-type diameter gauge was constructed and used in physiological experiments. The distinctive features of the design and use of the gauge may be summarized as follows. Installation of an image sensor in the focal plane of a single-lens reflex camera equipped with a set of extension tubes which makes it possible to measure outer diameters of blood and lymph vessels as small as 100 micrometer. Using the gauge, we can distinguish a diameter change of about 12 micrometer. Simultaneous measurements of the diameters of two different vessels can be made using two window signals generated independently at desired moments for appropriate periods within the video scans.

Animals↗
PubMed1980

An approach to the pathogenesis of "white finger" induced by vibratory stimulation: acute but sustained changes in vascular responsiveness of canine hindlimb to noradrenaline.

A fixed vibratory stimulation (60 Hz in frequency, 3 g in acceleration, and 2.2 mm in amplitude) was applied to a hindlimb (test limb) of dogs anaesthetised with sodium pentobarbital. Peripheral vascular resistance in the test limb was calculated as the ratio of mean pressure difference between the femoral artery and the femoral vein to the rate of femoral arterial blood flow. By means of a highly sensitive clinical thermometer, interdigital temperature was recorded not only from the test limb but also from a forelimb (control limb). The vibratory stimulation significantly reduced the peripheral resistance in the test limb. The increase in peripheral resistance induced by noradrenaline administration was suppressed during, and enhanced 1 h after, the stimulation. With the start of the vibratory stimulation, interdigital temperature in the test limb rose gradually and reached a constant level. The temperature first went below, and then returned to, the initial level after interruption of the stimulation. No change in the temperature was produced in the control limb. The decrease of temperature induced by noradrenaline administration was suppressed during, and enhanced 1 h after, the stimulation. These results indicate that, even in the living body, the conclusion of our previously report is valid: ie the responsiveness of arterial smooth muscle to noradrenaline decreases during, and increases soon after, vibratory stimulation. Assuming that our results obtained from acute experiments can be applicable to human digital arteries, the occurrence of "white fingers" on vibration disease may be understood in terms of vibration-induced hyperresponsiveness following stimulation.

Animals↗
PubMed1980

Active and passive mechanical characteristics of bovine mesenteric lymphatics.

Pressure-volume and pressure-radius relationships in lymphangions isolated from bovine mesenteric lymphatics were similar in pattern with those in the vein. Circumferential modulus of elasticity of the lymphatics ranged from 4.2 x 10(4) tatic walls. The contractile force increased in early stages of distension and decreased after an optimal intraluminal pressure was attained. The spontaneous activity was also affected by the rate of wall deformation. The pacemaker site of spontaneous activity seemed to be in the wall in the immediate vicinity of the inlet valve of a lymphangion. The activity propagated with a velocity of 4-5 mm/s. Ejection fraction of a lymphangion was between 45 and 65%. The endurance limit of the lymphatic valve was 68.4 +/- 7.6 cmH2O in specimens of about 3 mm in outer diameter. These findings suggested that lymphatic smooth muscle seemed to play a major role in elastic behavior of the wall and in regulation of the spontaneous activity, thereby affecting significantly passive and active lymph transport.

Animals↗
PubMed1980

Paradoxical relaxation of arterial strips induced by vasoconstrictive agents.

Longitudinal strips isolated from canine distributing muscular arteries were relaxed by noradrenaline and contracted by papaverine. This paradoxical relaxation and contraction may be due to a helical and circular arrangement of smooth muscle in the wall which is incompressible. Various vasoconstrictive agents, including noradrenaline, produced a circumferential contraction and longitudinal relaxation in muscular arteries. Vasodilator agents produced the opposite effect. The direction and magnitude of response of a helical strip to a vasoactive substance depended upon its sectioning angle from the transverse axis of the vessel.

Adenosine↗
PubMed1980

[The dynamics and its clinical significance of complement system, especially alternative pathway related to normal human pregnancy, delivery, puerperium and fetus (author's transl)].

The author studied human complement system, especially alternative pathway as a primitive biological defense system, in maternal serum during normal pregnancy, delivery and puerperium. The results obtained were as follows. 1. The mean value of hemolytic activity of alternative pathway (AlCH50) in healthy women was 18.3 +/- 1.1. This value was increased gradually in progress of gestational stages up to 26.6 +/- 2.3 of the average in the last trimester. Stochastically, significant differences about this value was noted between in the first trimester and in the last. This AlCH50 is decreased temporarily at delivery, and it was increased again rapidly, then went down to normal range about one month after delivery. 2. The average of immunochemical C3PA by SRID method during pregnancy was 22.5 +/- 0.4 mg/dl. It was significantly higher than the average 18.1 +/- 0.4 mg/dl of 59 healthy women. C3PA was noted to remain high level constantly during pregnancy. This C3PA level after delivery was observed to take a similar pattern as AlCH50. 3. beta 1C/1A globulin (C3) in 19 healthy women was 60.7 +/- 2.1 mg/dl. This C3 was also increased gradually during pregnancy up to maximum level of 87.5 +/- 2.8 mg/dl at the 3rd trimester. 4. Classical pathway (CH50, C4 and Cl INA) and fetal complement level were investigated at the same time and discussed here.

Adolescent↗
PubMed1979

A photoelectric diameter gauge utilizing the image sensor.

We have designed and constructed a blood vessel diameter gauge, utilizing a high resolving power and stability of the image sensor which has become of major interest lately as a new photoelectric transducer. The distinct feature of the gauge is summarized as follows. (1) Contact-free measurements of blood vessel diameter (1--14 mm) are possible. (2) The cuff-type probe is small in size and easy to put to use. (3) The lightguide consisting of optical fibers makes incident light cold. (4) The resolving power of the gauge is 28 micrometer in principle. (5) The frequency response of the gauge is flat up to 100 Hz. A few results of its preliminary application to in vitro and in vivo experiments are also demonstrated.

Animals↗