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Biomedical subjects

K Kanda

Publications and source records attributed to K Kanda.

At least 181 records · Page 10Linked to original sources
PubMed1984

Effects of nifedipine on total cardiac output distribution in conscious rat.

The purpose of this study was to determine the effects of the "calcium channel blocker" nifedipine (NF) on cardiocirculatory dynamics and the total distribution of cardiac output in the conscious rat preparation. Animals were instrumented for right atrial, left ventricular, arterial and venous pressure recordings and the radioactive microsphere technique was used to measure regional blood flow and cardiac output before (control) and during the i.v. infusion of either NF at three dosage levels [0.1, 0.6 and 1.5 mg (kg X hr)-1] or vehicle (ethyl alcohol and polyethylene glycol) at rates matching those of the NF protocol [0.015, 0.1 and 0.5 ml(min)-1]. The maximum rate of infusion represented approximately a 2% increase in blood volume per minute. Systemic vascular resistance, stroke volume, regional vascular resistances and the regional percentage of distribution of total cardiac output were calculated. In the experimental group (N = 7), NF at the highest dosage level lowered mean arterial pressure by 20% and resulted in a significantly lower systemic vascular resistance and left ventricular end diastolic pressure compared with the parallel vehicle control data. The parallel vehicle only slightly but significantly lowered heart rate. The most predominant circulatory effect of NF was a significant 64% reduction in coronary vascular resistance also reflected in a substantial increase in coronary blood flow. NF also dilated the hepatic arterial circulation. The net effects of NF on cardiac output distribution involved a significant fractional shift away from the cutaneous and splenic circulatory beds in favor of the coronary, hepatic arterial and gastrointestinal circulations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Reflex responses of human thigh muscles to non-noxious sural stimulation during stepping.

An investigation of reflex responses of leg muscles to sural stimulation during stepping was performed on human subjects. Non-noxious electrical stimulation applied during the swing phase or the latter half of the stance phase produced a mixed increase and decrease of EMG activity in the hamstring muscles. No response or very weak response was observed when the same stimulus was applied during either quiet standing or various levels of constant voluntary effort at varying hip and knee joint angles.

Adult↗
PubMed1983

Caldesmon, a calmodulin-binding, F actin-interacting protein, is present in aorta, uterus and platelets.

Caldesmon, a protein originally found in chicken gizzard, was concluded also to be present in bovine aorta, uterus, and human platelets by demonstration of a protein with the following properties: (a) Ca2+-dependent calmodulin-binding; (b) binding to F actin in such way that the binding was broken on Ca2+-dependent binding of calmodulin; (c) cross-reactivity in immune blotting procedures with affinity-purified antibody against gizzard caldesmon; (d) similar subunit Mr-values on SDS-gel to those of gizzard caldesmon. Like gizzard caldesmon, platelet caldesmon was composed of two polypeptide bands of Mr 150 000 and 147 000, but caldesmon in aorta and uterus gave a single band of Mr 150 000. A polypeptide of Mr 165 000 that was immunologically distinct from caldesmon but, like caldesmon, bound to calmodulin and F actin in a flip-flop fashion, was also demonstrated in aorta and uterus.

Animals↗
PubMed1983

Calmodulin-binding proteins that interact with actin filaments in a Ca2+-dependent flip-flop manner: survey in brain and secretory tissues.

Regulatory actions of calmodulin on the contractile apparatus and cytoskeleton of smooth muscle and nonmuscle tissue are mediated by a number of specific calmodulin-binding proteins that bind to F-actin in a flip-flop manner--i.e., they bind to calmodulin or F-actin depending on the presence or absence, respectively, of Ca2+. A survey for such proteins in brain, adrenal gland, and pituitary gland identified six polypeptides on polyacrylamide gels--Mr 340,000 (band 1), Mr 240,000/235,000 doublet (band 2), Mr 150,000 (band 3), Mr 129,000 (band 4), Mr 105,000 (band 5), and Mr 94,000 (band 6)--as flip-flop-regulated calmodulin- and F-actin-binding polypeptides. In addition to these polypeptides, a Mr 58,000 non-flip-flop calmodulin-binding actin-binding polypeptide (band 7) was found in all tissues examined. Band 2 was identified as calspectin (spectrin-related protein; fodrin). The flip-flop regulation of calspectin required the presence of a heat-labile nondialyzable factor contained in a supernatant fraction of brain homogenates. Band 1 was distinct from microtubule-associated proteins (MAPs) 1 and 2. However, when band 1 polypeptide was kept on ice 3 days, it converted to a lower molecular weight doublet that migrated with MAP2 on NaDodSO4 gel electrophoresis. Bands 1 and 2 were found in all tissues examined.

Actins↗
PubMed1983

Effect of tetanus toxin on the excitatory and the inhibitory post-synaptic potentials in the cat motoneurone.

Tetanus toxin (100 mouse minimal lethal doses per kilogram) was injected into the medial gastrocnemius muscle of the cat. At various times thereafter, homonymous and heteronymous group Ia excitatory post-synaptic potentials (e.p.s.p.s), disynaptic reciprocal Ia inhibitory post-synaptic potentials (i.p.s.p.s) and post-synaptic potentials (p.s.p.s) produced by sural nerve stimulation were recorded in the medial gastrocnemius motoneurones. The duration of the after-hyperpolarization, the input resistance and the axonal conduction velocity of motoneurones were also measured. Homonymous Ia e.p.s.p.s remained normal until 72 h after toxin injection. However, 5 days after toxin injection, the amplitudes of Ia e.p.s.p.s. were significantly smaller than those in control animals (1.5 +/- 1.0 mV versus 5.6 +/- 2.7 mV; t test, P less than 0.001). Heteronymous Ia e.p.s.p.s produced by stimulation of the lateral gastrocnemius-soleus nerve 5 days after toxin injection were also significantly smaller than those in control animals (0.6 +/- 0.6 mV versus 2.5 +/- 1.5 mV; P less than 0.001). However, these heteronymous Ia e.p.s.p.s remained normal when the lateral gastrocnemius-soleus nerve was ligated and sectioned at the entry to those muscles just before the toxin injection. The ascending volleys, which are supposed to represent mainly the action potentials of the dorsal spinocerebellar tract and to be elicited monosynaptically by collaterals of group I afferents, were essentially the same in the left tetanic and right control sides up to 5 days after toxin injection. Ia i.p.s.p.s and the hyperpolarizing component of sural p.s.p.s could not be produced or were very small in motoneurones sampled later than 30 h after toxin injection. The duration of the after-hyperpolarization and the input resistance of motoneurones remained normal. Axonal conduction velocity of motoneurones measured 5 days after toxin injection was 89.4 +/- 12.7 m/s, and was significantly slower than that of control motoneurones (94.1 +/- 15.4 m/s) (P less than 0.005). Differences in the amplitude of group I incoming volleys between tetanic leg and contralateral control leg were not observed. These results suggest that tetanus toxin blocks excitatory synapses in the central nervous system as well as inhibitory synapses.

Action Potentials↗
PubMed1983

[Combination chemotherapy with mitomycin C, methotrexate, and vincristine (MMV) for metastatic breast cancer refractory to adriamycin].

Twenty-five patients with metastatic breast cancer who had failed with combination chemotherapies including adriamycin were treated with a combination of mitomycin C, methotrexate, and vincristine (MMV). MMC 5 mg/m2, methotrexate 18 mg/m2, vincristine 0.7 mg/m2 were given i.v. on days 1 and 8, and repeated every 21 days. Seven patients (28%) experienced a partial response: 7 maintained NC and 11 failed to respond (PD). Median duration of regression was 12 weeks. Median survival time in PR patients was one year and 3 months, contrary to 6 months in patients with NC or PD. This combination was well tolerated except thrombocytopenia in 5 patients.

Adult↗
PubMed1982

Solubilization and partial purification of protein kinase systems from brain membranes that phosphorylate calspectin. A spectrin-like calmodulin-binding protein (fodrin).

In brain tissue a spectrin-like calmodulin-binding protein calspectin, or fodrin, is concentrated in a synaptosome fraction, where most of the calspectin is associated with the synaptic membranes. This endogenous calspectin was phosphorylated by protein kinase system(s) associated with the membranes. Here, we report the solubilization and partial purification of the membrane-associated calspectin kinase activity. The activity was resolved on a gel filtration column into two fractions, peaks I and II having estimated Mr of 800 000 and 88 000. The activity of peak I was dependent on the presence of both Ca2+ and calmodulin. Peak II revealed a basal activity in the absence of Ca2+ and calmodulin, which was stimulated 2-fold by addition of Ca2+. Calmodulin had no effect on the peak II activity.

Animals↗
PubMed1982

Actin polymerization induced by calspectin, a calmodulin-binding spectrin-like protein.

We have purified from a membrane fraction of bovine brain a calmodulin-binding protein (calspectin) that shares a number of properties with erythrocyte spectrin: It has a heterodimeric structure with Mr 240 000 and 235 000 and binds to (dimeric form) or crosslinks (tetrameric form) F-actin. We show that calspectin (tetramer) is capable of inducing the polymerization of G-actin to actin filaments by increasing nucleation under conditions where actin alone polymerizes at a much slower rate. Thus, brain calspectin behaves in the same manner as erythrocyte spectrin, supporting the idea that, in conjunction with actin oligomers it comprises the cytoskeletal meshwork underlying the cytoplasmic surface of the nerve cell.

Actins↗
PubMed1982

Ca2+-dependent binding of [3H]calmodulin to the microsomal fraction of brain.

The binding of calmodulin to a brain microsomal fraction rich in synaptic membranes and vesicles was studied using 3H-labeled calmodulin. The binding was Ca2+-dependent and highly specific to calmodulin since it was competitively displaced only by unlabeled calmodulin and not by 200-4,000-fold excess of other proteins that included troponin-C and S-100 protein. Within the physiological pH range, the specific binding, defined as the amount of bound [3H]calmodulin which is displacable by the addition of an excess of unlabeled calmodulin, agreed well with the Ca2+-dependent binding defined as the difference between the total binding in the presence of Ca2+ and the binding obtained with EGTA in place of Ca2+. Both binding activities appeared to be greatest at about pH 7.0. The binding, either specific or Ca2+-dependent, is a calmodulin concentration-dependent saturable process. The dose-dependent curve obtained for increasing concentrations of [3H]calmodulin agreed well with that obtained for mixtures of a fixed concentration of [3H]calmodulin and increasing concentrations of unlabeled calmodulin over the entire concentration range examined. The results serve as the basis for using [3H]calmodulin in binding studies. Scatchard plot analysis of the curve gave two different Kd values for calmodulin, 8.2 X 10(-8) and 5.3 X 10(-7) M. The corresponding maximum binding capacities were 1.0 X 10(14) and 1.6 X 10(14) calmodulin molecules per mg of microsomal protein, respectively. The binding ability of the microsomal fraction was completely abolished by prior treatment with proteolytic enzymes.

Animals↗
PubMed1982

Quantitative determinations of calmodulin in the supernatant and particulate fractions of mammalian tissues.

Although calmodulin is generally regarded as a soluble protein, a considerable amount of calmodulin activity was found to be associated with particulate fractions of mammalian tissues after an extensive washing of the particulate fraction with EGTA. Identity of this particle-bound and EGTA-nonextractable form of calmodulin with soluble calmodulin was established recently (Sobue, K., Yamazaki, R., Yasuda, S., & Kakiuchi, S. (1981) FEBS Lett. 129, 215-219). The particle-associated calmodulin activity was latent to some extent and its unmasking required the presence of nonionic detergent. We have developed an assay method for the soluble and particulate forms of calmodulin in biological samples and, by means of this method, concentrations of calmodulin in rat and bovine tissues were quantitatively determined. In the supernatant, high levels (greater than 10 microM) of calmodulin were found in the testis, pituitary gland, and various areas of brain, intermediate levels (5-10 microM) in the liver, kidney, and spleen. Particulate fractions contained 10-50% of the total calmodulin contents in the tissues. Human erythrocytes contained (2.5 +/- 0.2) microM calmodulin, or (14 +/- 0.9) X 10(4) calmodulin molecules per cell.

Adult↗