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Biomedical subjects

K Okabe

Publications and source records attributed to K Okabe.

At least 217 records · Page 12Linked to original sources
PubMed1987

Selective and long-lasting inhibitory actions of the dihydropyridine derivative, CV-4093, on calcium currents in smooth muscle cells of the rabbit pulmonary artery.

Effects of CV-4093, a newly synthesized dihydropiridine type of Ca antagonist, on membrane currents in enzymatically dispersed single smooth muscle cells of the rabbit main pulmonary artery were investigated using the single electrode voltage clamp method. Three types of membrane currents were evident, i.e., Ca and Na inward and K outward currents. CV-4093 potently inhibited the Ca inward current, as compared to findings with other currents. When the potential was at -60 mV, CV-4093 consistently inhibited the Ca current evoked by depolarization to 0 mV. However, a low concentration of CV-4093 (1-3 nM) enhanced the Ca current evoked by the depolarizing pulse of -20 mV, when the membrane potential was held at -80 mV. Inhibition of the Ca current induced by CV-4093 developed slowly and over 10 min was required to reach the maximum inhibition. Changes in the frequency of the depolarizing pulse did not modify the rate of inhibition induced by CV-4093. The inhibition was not restored by washout of the drug for over 40 min, and hyperpolarizations of the membrane did not accelerate the recovery. The IC50 of CV-4093 obtained for the K outward current was 3000 times larger than that obtained for the Ca inward current. CV-4093 apparently has highly selective and long-lasting inhibitory actions on the Ca current in smooth muscle cells of the rabbit main pulmonary artery.

Animals↗
PubMed1986

A newly identified Ca2+ dependent K+ channel in the smooth muscle membrane of single cells dispersed from the rabbit portal vein.

We found a new type of Ca2+-dependent K+ channel in smooth muscle cell membranes of single cells of the rabbit portal vein. A slope conductance of the current was 180 pS when 142 mM K+ solution was exposed to both sides of the membrane (this channel was named the KM channel, in comparison to the known KL and KS channels from the same membrane patch; Inoue et al. 1985). This KM channel was less sensitive to the cytoplasmic Ca2+ concentration, [Ca2+]i, but was sensitive to the extracellular Ca2+, [Ca2+]o, e. g. in the outside-out membrane patch, lowering the [Ca2+]o in the bath markedly reduced the open probability of this channel, and also in cell-attached configuration, lowering of the [Ca2+]o using the internally perfused patch clamp electrode device reduced the opening of KM channel. TEA+ (1-10 mM) reduced the amplitude of the elementary current through the KM channel applied from each side of the membrane, but this agent inhibited the KM channel to a greater extent when applied to the inner than to the outer surface of the membrane. Furthermore, this KM channel had a weak voltage dependency, and the open probability of the channel remained much the same within a wide range of potential (from -60 mV to +60 mV). Whereas most Ca2+-dependent K+ channels are regulated mainly by [Ca2+]i and possess a voltage dependency, these properties of the KM channel differed from other Ca2+-dependent K+ channels.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Correction of the inverted nipple.

A simple procedure for correction of inverted nipples is described. The key to the method is the preparation of 2 deepithelized dermal flaps after supplementing the volume of tissue beneath the nipple, and preventing recurrence of the deformity with slings.

Breast↗
PubMed1986

Direction of suture lines in Z-plasty scar revision.

Conventional methods of Z-plasty, a basic technique of plastic surgery, are incorrect since they are based on the assumption that the suture lines as designed prior to Z-plasty and those that actually result will coincide. For Z-plasty to be satisfactorily applied in scar revision, sufficient thought must be given to the actual directions in which the suture lines will lie in comparison with those envisioned.

Cicatrix↗
PubMed1986

Significance of deep body thermometer for assessing haemodynamics of free flaps.

A deep body thermometer was used in 13 cases of microvascular tissue transfer in order to assess the post-operative haemodynamics of the flaps. Nine of 10 cases involving free skin flaps demonstrated good blood flow by the temperature recovery curves in cooling and rewarming (CR) tests conducted immediately and 6 to 12 hours after operation but in the tenth, anastomotic problems were predicted by the tests. None of the three musculocutaneous flap cases demonstrated good blood flow patterns initially but two were good at 6 hours and did well. The third had a poor pattern at 6 hours and suffered partial necrosis. This study confirmed that it is possible to assess the state of circulation in a flap by the CR test after free flap transfer.

Adolescent↗
PubMed1986

The Z in Z-plasty must have a long trunk.

Erroneous thinking in regard to Z-plasty, which is a fundamental technique in plastic surgery, has been pointed out. In most cases of Z-plasty, the trunk of the Z should be designed longer than the two limbs.

Adolescent↗
PubMed1986

Protective effect of prostaglandin I2 on hepatic mitochondrial function of the preserved rat liver.

Mitochondrial function of the liver is one of the limiting factors in liver preservation. Nowadays, prostaglandin I2 (PGI2) is used as a cytoprotective agent in liver preservation without full understanding its mechanism involved. It is the objective of the present study to evaluate the protective effect of PGI2 on mitochondrial function of the rat liver during hypothermic preservation. Collins' solution was used as a preservation solution and PGI2 was added to it in some experimental groups. Both ischemic and non-ischemic livers were perfused with the preservation solution and preserved under simple hypothermia for 8 hr. Parameters of the mitochondrial function such as respiratory control, oxygen consumption rate in state 3 respiration, ADP/O ratio and the rate of ATP synthesis were decreased significantly after 8 hr hypothermic preservation, even if ischemic injury was not induced prior to preservation. ADP/O ratio, which represents the efficiency of oxidative phosphorylation in mitochondria, was improved significantly (p less than 0.01) when PGI2 was used as a cytoprotective agent. The rate of ATP synthesis, a parameter of energy producing reaction, showed a tendency to be increased by PGI2, but was not significant. It was concluded that hypothermic preservation of the rat liver is associated with the deterioration of the mitochondrial function and PGI2 has a favorable effect on the impaired ADP/O ratio of oxidative phosphorylation in mitochondria.

Adenosine Triphosphate↗
PubMed1986

Blood purification of bilirubin and bile acids by plasma exchange for patients with liver failure.

To evaluate the efficacy of blood purification by plasma exchange in patients with liver failure, blood levels of total bilirubin and total bile acids, known to be a part of protein-bound toxins, were measured before and after plasma exchange. With one plasma volume exchange the percent reduction was 39 for bilirubin and only 25 for bile acids. The declining of the reduction efficiency appeared to be well correlated with the prolongation of the treatment time for bilirubin and the augmentation of the initial concentration for bile acids. These data suggested that the equilibration between intra-and extra-vascular pool takes place slowly for bilirubin and comparatively rapidly for bile acids, though they are both mostly bound to albumin in the blood. In addition, the presence of protein-bound toxins like bile acids, predominantely accumulated in the tissue, may make it more difficult to support patients with liver failure by only blood purification therapy with plasma exchange.

Adult↗