Search PubMed⌕ Search

Biomedical subjects

T Takabatake

Publications and source records attributed to T Takabatake.

At least 109 records · Page 6Linked to original sources
PubMed1983

Activation of tubuloglomerular feedback in rat nephrons by sera from rabbits with fulminant hepatic failure.

Experiments were designed to determine whether substance(s) other than electrolytes might activate tubuloglomerular feedback in experimental fulminant hepatic failure. Severe hepatic damage and renal dysfunction were induced by intravenous administration of D-galactosamine. Sera from normal or D-galactosamine-treated rabbits were dialyzed against glucose solution to reduce electrolyte concentrations. Tubuloglomerular feedback response was evaluated in rat nephrons by measuring the early proximal flow rate (EPFR) during orthograde perfusion of the loop of Henle. EPFR was reduced by 28 and 48% with Ringer's solution and sera from D-galactosamine-treated rabbits, respectively, but was not altered by normal sera. Substance(s) other than electrolytes in the sera from D-galactosamine-treated rabbits might activate the tubuloglomerular feedback to reduce glomerular filtration.

Animals↗
PubMed1982

Antihypertensive effect of nicardipine hydrochloride in essential hypertension.

The antihypertensive effect of a new calcium antagonist, nicardipine hydrochloride (YC-93), was studied in 47 mild to moderate essential hypertensives. YC-93 (30-60 mg/day) was administered orally alone for 8 weeks (Group I, 31 patients) or in combination with diuretics, beta blockers, or both (Group II, 16 patients). Blood pressure was reduced from 173.6 +/- 2.2/103.5 +/- 1.7 to 139.7 +/- 2.0/87.2 +/- 1.1 mmHg in Group I and from 172.9 +/- 3.9/108.9 +/- 2.9 to 140.5 +/- 2.3/89.5 +/- 2.5 mm Hg in Group II. Pulse rate was not altered in Group I but increased transiently in Group II. The side effects seen in seven patients were mostly related to the vasodilatation and were generally transient and mild. These results indicate that YC-93 is an effective antihypertensive drug for the treatment of essential hypertension.

Adult↗
PubMed1982

Feedback regulation of glomerular filtration rate in the denervated rat kidney.

Micropuncture studies were done in anesthetized rats to determine whether the sensitivity of tubuloglomerular feedback might be modified by acute renal denervation. The proximal single nephron glomerular filtration rate (SNGFR) was significantly greater than the distal SNGFR was, when measured in a paired manner from the same nephron. Early proximal flow rate (EPFR) was measured during orthograde perfusion of the loop of Henle with Ringer's solution. A change of loop perfusion rate from 0 to 40 nl/min decreased EPFR in normal, sham-denervated, and denervated kidneys. The differences between proximal and distal SNGFR and the percent reduction of EPFR were not different among the three groups. These results indicate that the sensitivity of the tubuloglomerular feedback may not be affected by acute denervation.

Animals↗
PubMed1981

Daily profile of baroreflex sensitivity and the variability of blood pressure in essential hypertensive patients.

1. We have monitored intra-arterial pressure continuously throughout the day and analysed every beat by computer. 2. Baroreflex sensitivity (ms/mmHg) was measured four times a day (07.00, 12.00, 17.00 and 20.00 hours) in seven patients and three times a day (07.00, 12.00 and 17.00 hours) in 23 patients. The diurnal variation of baroreflex sensitivity in individual patients was 0--5.3 ms/mmHg and was not consistent. Mean baroreflex sensitivity was reduced in hypertensive patients compared with normotensive subjects. 3. A negative correlation was seen between baroreflex sensitivity and the variability of systemic blood pressure. 4. Baroreflex sensitivity was well correlated with the variability of heart rate.

Adult↗
PubMed1978

The early phase of experimental acute renal failure. III. Tubologlomerular feedback.

Experiments were designed to determine whether tubologlomerular feedback, which modifies nephron filtration rate in response to alterations in the macula densa sodium chloride concentration, was still apparent in the initiation phase of various types of acute renal failure. The response of the glomerulus to changes in the macula densa stimulus was evaluated in haeme pigment, ischaemic and nephrotoxic induced renal damage by measuring early proximal flow rates. The sodium chloride concentration at the macula densa was varied between low values and isotonicity in two ways: firstly, by interruption of flow through the loop of Henle, followed by orthograde perfusion with Ringer's solution; secondly, by retrograde perfusion of the loop of Henle with isosmotic mannitol or Ringer's solution. In all nephrons examined, filtration rate was inversely correlated to the macula densa sodium chloride concentration, except during orthograde perfusion with 10(-4) M furosemide in Ringer's solution, when, despite the high sodium chloride concentration, filtration rate remained high. It is concluded that the mechanism of tubuloglomerular feedback is viable after the onset of compromised renal function, and may, as postulated, account for the reduction in blood flow and nephron filtration rate occurring in acute renal failure.

Acute Kidney Injury↗
PubMed1977

The early phase of experimental acute renal failure. I. Intratubular pressure and obstruction.

Tubular obstruction in acute renal failure, postulated to cause the restricted excretory function, is suggested by raising intratubular pressure, to lower effective filtration pressure and diminish urine output. To examine the applicability of the obstruction hypothesis to the pathogenesis of experimental acute renal failure, proximal intratubular pressure and renal function were measured after renal insults of different origins and severity. Obstruction in acute renal failure kidneys should manifest itself as an increase in intratubular pressure for a least 12 h, for within this time period following ureteral occlusion, elevated pressures were found to reflect obstruction. The consistent existence of raised proximal intratubular pressure in acute renal failure kidneys could not be detected; ischaemic and nephrototoxic models were found in which no rise in intratubular pressure could be demonstrated. The oliguric nature of acute renal failure kidneys could not be verified; ischaemic and nephrotoxic models were found in which urine output was either normal or enhanced. Only for methaemoglobin induced renal failure were raised intratubular pressure, oliguria and casts concurrent. It is concluded that obstruction is not a consistent feature of experimental acute renal failure and that the obstruction hypothesis may be specifically applicable to only a few models, which include haeme pigment and folic acid induced renal failure.

Acute Kidney Injury↗
PubMed1977

The early phase of experimental acute renal failure. II. tubular leakage and the reliability of glomerular markers.

Experiments were designed to determine whether leakage of substances across the tubular epithelium, which are impermeant in the normal kidney, falsifies the measurement of glomerular filtration rate in acute renal failure. Permeability to those substances most commonly used for filtration rate determination, polyfructosan, inulin and ferrocyanide, was estimated by measuring their recoveries following perfusion through various nephron segments in haeme pigment, ischaemic and nephrotoxic models of acute renal failure. Late proximal recovery of 14C ferrocyanide was only marginally decreased compared to controls, by a maximum of 6%. Distal recovery of polyfructosan, 14C and 3H inulin were depressed somewhat more, by a maximum of 11%. Urinary recovery of 14C inulin was reduced by only 15% in kidneys showing severely restricted renal function. It is concluded that tubular leakage is not a feature of significance in the early phase of moderate acute renal failure, that ferrocyanide and inulin are reliable markers for the determination of nephron filtration rate and water reabsorption, and that the reduction in whole kidney inulin or polyfructosan clearance reflects primarily a reduction in glomerular filtration rate.

Acute Kidney Injury↗
PubMed1977

Effect of acute unilateral renal denervation on tubular sodium reabsorption in the dog.

The effects of acute denervation of the kidney on renal tubular sodium and water excretion were studied in anesthetized, hypophysectomized, and cortisone-treated mongrel dogs during stable water diuresis produced by the infusion of 2.5% dextrose. In all experiments, denervation natriuresis, and diuresis were observed without significant change in glomerular filtration rate (GRF) and renal plasma flow (RPF). Fractional sodium delivery to the distal nephron (CNa + CH2O/100 ml GFR) and fractional free water clearance (CH23/100 ml GFR) was significantly greater in the denervated kidney compared with the innervated kidney (9.6+/-1.2 vs. 6.7+/-0.9% and 8.8+/-1.2 vs. 6.5+/-0.8%, respectively). Distal tubular sodium reabsorption (CH2O/(CNa + CH2O)) was not significantly different. We conclude that renal denervation primarily affects the proximal tubule as manifested by a decrease in the reabsorption of sodium and water. A small effect of denervation on the distal nephron is not completely ruled out.

Animals↗