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Biomedical subjects

Y Abe

Publications and source records attributed to Y Abe.

At least 1,189 records · Page 66Linked to original sources
PubMed1977

Effects of glucagon on the renal hemodynamics of dogs.

An intrarenal infusion of glucagon resulted in an increase of glomerular filtration rate (GFR) with the same order of magnitude of renal blood flow (RBF) but did not affect the intrarenal distribution of blood flow. A superimposition of acetylcholine and glucagon decreased GFR even though RBF increased significantly. These findings indicate that the effect of glucagon on GFR depended on the selective dilation of afferent arterioles without any change in permeability of glomerular capillaries and redistribution of filtration.

Acetylcholine↗
PubMed1977

Control of renin secretion.

The present study was designed to examine the interrelationship between the intrarenal vascular receptor and the sympathetic nerve, beta-adrenergic system, for renin secretion in the anesthetized dog. 1) A reduction in renal arterial pressure from a control pressure to 100 mmHg changed neither ther flow rates of all cortex zones nor renin secretion. Further reduction of renal arterial pressure to 75 mmHg resulted in a significant increase of renin secretion and a decrease of blood flow in the outer cortex. Intrarenal arterial infusion of norepinephrine at a control pressure increased a renin secretion. However, norepinephrine infusion at a reduced pressure suppressed the renin release with a recovery of the vascular resistance to the control level. These results suggest that the changes in the degree of blood flow and pressure in the renal afferent arterioles are not essential for the renin secretion,but renin secretion by the pressure reduction might be related to the autoregulatory capacity of afferent arterioles in the outer cortex. 2) At 5 min of hemorrhagic period (75 mmHg) arterial PRA elevated in control, and phenoxybenzamine and propranolol treated groups and any significant difference in responses was not observed among groups. However, at 60 min of hemorrhagic hypotensive period PRA in control and phenoxybenzamine treated groups further increased, but PRA in propranolol treated group was not alter from its 15 min value. These results indicated that the roles of vascular receptor and renal sympathetic nervous sytem in receptor and renal sympathetic nervous system in renin secretion might be separated, and that the renal sympathetic nervous system did not relate to the early response of renin release, but related to the late response. 3) Intrarenal arterial infusion of cAMP and DbcAMP resulted in a significant increase of renin release. In addition, CaC12 solution was infuesed into the renal artery and a significant rise in renal venous PRA was observed within 5 min of infusion. These data suggested that a beta-adrenergic receptor-adenyl cyclase-cAMP system was involved in the control of renin secretion, and that since the intracellular effect of cAMP was partly related to the change of intracellular Ca distribution, its change resulted in an increase in renin secretion.

Animals↗
PubMed1977

Effects of glucagon on the renal hemodynamics in the dog.

The effect of glucagon on the renal hemodynamics in the dog was examined by comparing its effect with that of secretin, a peptide with which glucagon shares a similar chemical structure. An intrarenal infusion of glucagon resulted in increases of RBF and GFR. GFR rose by approximately the same order of magnitude of RBF. The increase in GFR depended on the selective dilation of the afferent arteriole and a consequent rise in the transcapillary pressure difference. On the other hand, secretin infusion produced highly significant and proportional decreases in both afferent and efferent arteriolar resistance, resulting in no change in GFR. A superimposition of acetylcholine to glucagon decreased GFR even though RBF increased significantly. Glucagon infusion did not affect the permeability of glomerular capillary and the distribution of cortical blood flow. These findings indicate that the effect of glucagon on GFR depended on the selective dilation of afferent arteriole, and that as a result of its dilation the net filtration pressure increased without any change in permeability of glomerular capillary and a redistribution of filtration.

Acetylcholine↗
PubMed1977

[Effects of secretin on renal functions in the dog].

In anesthetized mongreal dogs, the intrarenal arterial (0.2 approximately 1.0 unit/kg-min) and the intravenous infusion (0.4 approximately 2.0 unit/kg-min) of secretin caused dose-dependent increase of RBF, accompanied by decreases of the calculated afferent arteriolar resistance (Ra) and efferent arteriolar resistance (Re), but produced no significant effect on GFR, urine flow, electrolyte excretion, osmolar clearance and free water reabsorption. The distribution of cortical blood flow was examined using the radioactive microsphere technique. The intrarenal infusion of secretin (1.0 unit/kg-min) increased renal cortical blood flow in the juxtamedullary area much more than in the superficial area, shifting the blood flow from the outer to the inner zone. Simultaneous intrarenal infusion of secretin (1.0 unit/kg-min) and glucagon (0.5 microng/kg-min) produced increases in GFR, urine flow and electrolyte excretion to a lesser degree than those induced by glucagon alone, whereas the increment in RBF and the decreases in Ra and Re were almost to the same degree as those caused by secretin alone. The present results indicate that secretin produces the dilation of afferent and efferent arterioles, resulting in an increase in RBF, with no change in GFR and urine flow, and that the effects of glucagon on renal functions are masked by secretin mainly through the effects of renal hemodynamics.

Animals↗
PubMed1977

[Studies of calcium phosphate glass-ceramics--development of dental materials. (Part 2) Acid resistance--(author's transl)].

It is well known that minerals of bone or tooth are essentially of CaO-P2O5 system. Glass and the crystallized product, i.e., so-called "glass-ceramics" of which chemical composition is 55 CaO . 45 P2O5 (in mole %) and have been developed for biomaterials were subjected to chemical durability test. Human enamel was also tested for the comparison of the data with them. All the specimens were ground to powders in size from 74 to 140 micrometer. A hundred milligram of the powders were immersed into 100 ml. of N/10 acetate buffer (1 mol acetic acid) solution (pH 4.1) at a constant temperature of 37 degrees C. Amount of Ca2+ and P5+ dissolved were determined by an atomic absorption method and Fiske-Subbarow method, respectively. The order of dissolution is human enamel greater than glass greater than glass-ceramics: the amount of Ca2+ (SCa) and P5+ (Sp) with soaking time (t) was expressed by the following equations, :formula: (see book). The glass and the glass-ceramics show good resistance against a weak acid.

Acids↗