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Biomedical subjects

H Hashimoto

Publications and source records attributed to H Hashimoto.

At least 1,117 records · Page 62Linked to original sources
PubMed1987

Alterations in the microvasculature of one-kidney, one-clip hypertensive rats.

The microcirculation was studied in the cremaster muscle of one-kidney, one-clip (1K-1C) hypertensive rats and uninephrectomized controls under chloralose-urethan anesthesia 1-2, 4-5, or 8-9 wk following renal artery stenosis. With the use of television microscopy, inside and outside diameters of first (1A) through fourth-order (4A) arterioles were measured before and after vasodilation with 10(-4) M adenosine. Mean arterial blood pressure was significantly elevated in the 1K-1C rats, rising to 170 +/- 6 mmHg by 8-9 wks vs. 93 +/- 2 mmHg in controls. Enhanced vasoconstriction, resulting in closure of arterioles, appeared only in the smaller arterioles of 1K-1C and diminished throughout the development of hypertension. Structural rarefaction appeared later and increased with the development of hypertension. Vasodilated inside diameters of control, but not 1K-1C, 1A, 2A, and 3As, increased with increasing age, leaving the hypertensive arterioles with structurally reduced lumens and increased wall-to-lumen ratios, but without increases in wall cross-sectional areas. Structural lumen reduction appeared first in the 1A and advanced downstream as hypertension developed. Thus vasoconstriction of the smallest arterioles is important initially in renal hypertension, but structural alterations become more important later.

Adenosine↗
PubMed1987

Comparison of vasodilator effects of DN-9693, a selective inhibitor of cyclic AMP phosphodiesterase, and isobutylmethylxanthine, a non-selective one, in dogs.

The present experiments were performed in anesthetized dogs in order to determine if DN-9693, a new antiplatelet agent known to selectively inhibit cyclic AMP phosphodiesterase (PDE), and isobutylmethylxanthine (IBMX), which inhibits both cyclic AMP and GMP PDEs, have different cardiovascular actions. With intra-arterial administration into the left anterior descending coronary, femoral, cranial mesenteric and renal arterial beds perfused at constant pressure with autologous blood, both agents increased blood flow in a similar dose range. DN-9693 was longer-acting than IBMX. Both agents were nearly equi-effective in the femoral circulation, but DN-9693 was 1.5-2 times less effective than IBMX in the others. With intravenous administration, both agents were equi-effective in increasing the maximum rate of rise of left ventricular pressure heart rate and myocardial oxygen consumption and in reducing mean blood pressure. However, DN-9693 was less effective in increasing coronary sinus outflow than IBMX. These results suggest the following: 1) Vasodilation in the somatic rather than the visceral circulation is important in reducing mean blood pressure. 2) Cyclic GMP may not be involved in the cardiac action of PDE-inhibitors. 3) Cyclic GMP may be involved in the vasodilator effect of PDE-inhibitors in the coronary, mesenteric and renal circulations but least involved in the femoral circulation.

1-Methyl-3-isobutylxanthine↗
PubMed1987

Changes in vascular responsiveness to vasoactive agents in the hindlimb of DOCA-salt hypertensive rats.

The responsiveness to vasoactive agents in the perfused hindlimb of DOCA-salt hypertensive rats was examined and compared with that of normotensive rats. The vasoconstrictor responses in the femoral vascular bed to norepinephrine and serotonin were markedly potentiated in DOCA-salt hypertensive rats as compared with those in normotensive rats, and no change was found in the responses to angiotensin II. On the other hand, the vasodilatory response in DOCA-salt hypertensive rats to isoproterenol was attenuated without any marked changes in responsiveness to acetylcholine, nitroprusside and papaverine. These results suggested that the reduced vasodilator responses as well as the increased vasoconstrictor responses occur to some specific vasoactive agents in DOCA-salt hypertensive rats.

Angiotensin II↗
PubMed1987

Effects of 2-[(5-chloro-2-methoxyphenyl) azo]-1H-imidazole (M6434) on alpha adrenergic receptors.

The effects of a newly synthesized compound, 2-[(5-chloro-2-methoxyphenyl)azo]-1H-imidazole (M6434) on alpha-adrenergic receptors were investigated by using the atria of normal and hypothyroid rats, rat vasa deferentia and canine arteries. M6434 showed a positive inotropic effect on rat left atria, which was suppressed by phentolamine but not by propranolol and reserpine. M6434 also showed a positive chronotropic effect on rat right atria. These positive inotropic and chronotropic effects of M6434 were enhanced in propylthiouracil-induced hypothyroid rats. M6434 caused contraction of rat vas deferens and increased its spontaneous movement. These effects on vas deferens were suppressed by phentolamine. M6434 induced contraction of canine arteries. The pD2 values for vasoconstrictive effects of M6434 on the aorta, pulmonary artery, renal artery and femoral artery were about equal to those of phenylephrine, and the intrinsic activity of M6434 was somewhat lower than that of phenylephrine. These results suggest that M6434 is an adrenergic alpha-agonist which is about as potent as phenylephrine and that M6434 has neither a beta-stimulating activity nor a catecholamine-releasing one.

Animals↗
PubMed1987

Microvascular density changes during wound-healing.

Vessel densities of arterioles, capillaries, venules and A-V anastomoses were determined during wound-healing following implantation of the rabbit ear chamber. Arterioles were defined on the basis of the direction of blood flow and the presence of a muscular coat. Capillaries were endothelial cell tubes with single-file flow of erythrocytes. Venules were thin-walled vessels collecting blood flow from capillaries and carrying blood flow from the tissue. A-V anastomoses were thick-walled, unbranched vessels carrying blood flow from an arteriole to a venule. Arteriolar density was relatively higher in the earlier stages but venular density was higher in the later stages of wound-healing. The fractional density was highest 2 weeks after implantation for arterioles (17.9%), at 4 weeks for capillaries (39.3%), and at 10 weeks for venules (56.9%). No significant change was observed in the density of A-V anastomoses. This study suggests that the rates of growth and decay are different among each vessel category during wound-healing.

Animals↗
PubMed1987

[A case of a carcinoid of the duodenum (somatostatin-, serotonin- and ACTH-producing) with carcinoma of the stomach].

A case of a duodenal carcinoid which was producing somatostatin, serotonin and ACTH in a 65-year-old man is reported. The patient was found to have a submucosal protruded mass of the duodenal bulb and a tumor mass-like IIa + IIc in the antral portion of the stomach. Subtotal gastrectomy was performed and the histological diagnosis of the tumors were found to be a classical carcinoid of the duodenum and a well-differentiated tubular adenocarcinoma of the stomach. The carcinoid cells of the duodenum had numerous cyto-plasmic granules which were positive by Grimelius staining and negative by Hellerström-Hellmann staining, and 200-300 nm in size, electronmicroscopically. These cells were shown to contain somatostatin, serotonin or ACTH-positive cells by means of monoclonal immunohistochemistry, however, results were negative for gastrin, insulin, glucagon, calcitonin, VIP or PP.

Adenocarcinoma↗
PubMed1987

Potassium perchlorate, potassium iodide, and propylthiouracil: promoting effect on the development of thyroid tumors in rats treated with N-bis(2-hydroxypropyl)-nitrosamine.

The effect of 1000 ppm potassium perchlorate (KClO4), 1000 ppm potassium iodide (KI) or 1000 ppm propylthiouracil (PTU) in the diet on the development of thyroid tumors was studied histologically and biochemically in Wistar rats given a single ip injection of 280 mg of N-bis(2-hydroxypropyl)nitrosamine (DHPN) per 100 g body weight. Basal diet containing 100 ppm KClO4, 1000 ppm KI or 1000 ppm PTU was given for 19 weeks from week 2 to week 20. The incidence of thyroid adenomas at the end of week 20 of the experiment was 100% (20/20) in rats treated with DHPN followed by KClO4, 85% (17/20) in rats given DHPN followed by KI, 95% (19/20) in rats given DHPN followed by PTU, and 5% (1/20) in rats given DHPN alone. The incidence of thyroid cancers was 100% (20/20) in rats treated with DHPN followed by KClO4, 65% (13/20) in rats treated with DHPN followed by KI and 0% (0/20) in rats treated with DHPN followed by or not followed by PTU. Rats given KClO4, KI or PTU alone and untreated rats had no thyroid tumors. The mean values of TSH in serum were 2.94 +/- 0.79 ng/ml in rats treated with DHPN followed by KClO4, 9.40 +/- 16.0 ng/ml in rats treated with DHPN followed by KI and 60.94 +/- 20.60 ng/ml in rats treated with DHPN followed by PTU. It was confirmed that (1) KClO4, PTU and KI promote the development of thyroid tumor in rats treated with DHPN, (2) the promoting effect of KClO4 or KI is stronger than that of PTU and (3) the value of TSH in serum is not parallel to the promoting effect on the development of thyroid tumor.

Animals↗