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Biomedical subjects

M Tanno

Publications and source records attributed to M Tanno.

At least 91 records · Page 5Linked to original sources
PubMed1986

Effects of sodium and angiotensin II on urinary active and inactive kallikrein in rats.

To assess possible relationships between sodium balance, angiotensin II (ANG II), and renal active and inactive kallikrein, we studied the effects of sodium loading with 1% NaCl and chronic ANG II infusion (900 micrograms/kg per day) on the urinary excretion of total and active kallikrein for 6 days in conscious rats. We determined urinary total, active and inactive kallikrein by measuring kallikrein activity using a kininogenase assay before and after treatment with trypsin (200 micrograms/ml). Sodium loading produced a sustained increase in urinary total, active and inactive kallikrein excretion. Chronic infusion of ANG II induced a sustained increase in urinary total, active and inactive kallikrein excretion in rats on a regular diet. In rats loaded with sodium, however, ANG II did not induce any further changes in urinary kallikrein excretion. Thus, the present study suggests that both sodium loading and ANG II infusion might stimulate the synthesis of renal kallikrein. In addition, it is suggested that ANG II infusion might stimulate the synthesis of kallikrein, at least partly, via the same mechanism as sodium loading does.

Angiotensin II↗
PubMed1986

Effects of ouabain on blood pressure regulation in rats.

In order to test the hypothesis that a circulating inhibitor of the sodium-potassium ATPase pump may cause a concomitant rise in blood pressure and increased sodium excretion, we studied chronic effects of continuous infusion of ouabain, an inhibitor of sodium-potassium ATPase, for up to 6 days on systolic blood pressure and urinary sodium excretion in conscious rats. We also evaluated the effect of this substance in rats with hypertension induced by chronic infusion of norepinephrine. Continuous infusion of ouabain (1.2 mg/kg per day) into the jugular vein by an osmotic minipump did not induce any changes in systolic blood pressure and urinary sodium excretion in intact rats on regular diets. Furthermore it did not cause a change in systolic blood pressure in rats drinking 1% NaCl, and in unilaterally nephrectomized rats drinking 1% NaCl, when compared with vehicle-infused animals. When the same dose of ouabain was administered simultaneously with 1.8 mg/kg per day norepinephrine infused intraperitoneally by another osmotic minipump in conscious rats, systolic blood pressure rose on day 1 to only 129.3 +/- 2.8 mmHg compared with the rist to 145.0 +/- 2.0 mmHg when norepinephrine alone was infused (P less than 0.01). The antihypertensive effect of ouabain was sustained for the entire experimental period lasting for 6 days and was not associated with any changes in urinary sodium excretion. The administration of ouabain to rats made hypertensive by a 3-day infusion of norepinephrine, returned the blood pressure to control levels, and the antihypertensive effect was sustained throughout the experimental period lasting a further 3 days and was not associated with any changes in urinary sodium excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Effect of atrial natriuretic factor on angiotensin II-induced hypertension in rats.

To assess the physiological role of atrial natriuretic factors in blood pressure regulation, we studied the effect of chronic infusion of a synthetic atrial natriuretic factor of 25 amino acid residues (Arg 102-Tyr 126) in rats with angiotensin II-induced hypertension. Rats were studied while on a normal sodium diet or during sodium loading with 1% NaCl solution used as drinking water. Systolic blood pressure decreased slightly during combined infusion of synthetic atrial natriuretic factor, 150 micrograms/kg/day, and angiotensin II, 900 micrograms/kg/day. This effect was sustained for 3 days in rats receiving a regular sodium intake (p less than 0.01) and during sodium loading (p less than 0.01). Administration of synthetic atrial natriuretic factor to rats made hypertensive by a 3-day infusion of angiotensin II reduced blood pressure slightly, but not to control levels, and this effect was sustained for the remaining 3 days of the experiment in both dietary groups. These results indicate that a nonhypotensive dose of synthetic atrial natriuretic factor can modulate the vasopressor effect of angiotensin II. Thus, the attenuating effect may be involved in blood pressure regulation independently of sodium metabolism, although its actual physiological importance remains undetermined.

Angiotensin II↗
PubMed1986

Atrial natriuretic factor and cyclic guanosine 3',5'-monophosphate in vascular smooth muscle.

To elucidate the molecular mechanism of the vascular action of atrial natriuretic factor (ANF), we investigated the effects of synthetic ANF and sodium nitroprusside on the levels of intracellular cyclic nucleotides and prostacyclin (measured as its stable metabolite 6-keto-prostaglandin F1 alpha) in cultured vascular smooth muscle cells from rat mesenteric artery and, in some experiments, from rat renal artery. Both ANF and sodium nitroprusside increased intracellular cyclic guanosine 3',5'-monophosphate (cGMP) levels in a dose-dependent manner but did not affect cyclic adenosine 3',5'-monophosphate levels or 6-keto-prostaglandin F1 alpha synthesis. The stimulatory effect of ANF and sodium nitroprusside on cGMP levels were additive. Neither the deprivation of extracellular Ca2+ nor calcium entry blockers affected ANF-stimulated cGMP levels. Preincubation of ANF or sodium nitroprusside with kallikrein attenuated only the effect of ANF on cGMP levels. The effect of kallikrein was abolished by serine protease inhibitors. In contrast, the oxidant methylene blue inhibited the effect of sodium nitroprusside on cGMP levels, but not that of ANF. The stimulatory effect of ANF on cGMP levels was greater in cells from renal artery than in those from mesenteric artery. These results in cultured vascular smooth muscle cells further support the hypothesis that cGMP mediates the vasorelaxant action of ANF.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Antihypertensive effect of synthetic atrial natriuretic factor in vasopressin-infused rats.

To assess the pathophysiological role of atrial natriuretic factors in the regulation of blood pressure, we studied the effect of chronic infusion of a synthetic atrial natriuretic factor of 25 amino-acid residues on blood pressure and sodium-water excretion. Experimental subjects were rats with hypertension made by chronic infusion of vasopressin on regular intakes of sodium or on sodium loading with 1% NaCl as drinking water. When a subdepressor dose (150 micrograms/kg/day) of synthetic atrial natriuretic factor was delivered via an osmotic minipump into the jugular vein simultaneously with 7.2 U/kg/day of vasopressin infused intraperitoneally by another osmotic minipump, the expected elevation of systolic blood pressure was completely inhibited. This was not accompanied by any changes in urine volume and urinary sodium excretion. The antihypertensive effect was sustained throughout the experimental period lasting 3 days in rats on regular sodium intake (p less than 0.01) or on sodium loading with 1% NaCl as drinking water (p less than 0.01). These results indicate that a subdepressor dose of synthetic atrial natriuretic factor can modulate the vasopressor effect of vasopressin. Therefore it is suggested that an atrial natriuretic factor may be involved in the regulation of blood pressure via its antagonizing effect to vasopressin.

Animals↗
PubMed1986

[Evaluation of thallium-201 myocardial emission computed tomography based on a comparison with postmortem findings].

The correlative study of myocardial perfusion assessed by 201Tl myocardial ECT with the pathological finding of the heart was performed in 10 autopsied cases with mean age of 77 years old (range: 60-90 y). In 6 cases with myocardial infarction (MI) 7 perfusion defects were observed, that was, 3 in anteroseptal wall, 1 in anterolateral wall and 3 in posterior wall on the images of SPECT. Seven MIs were also found in postmortem examination. Six MIs were observed at autopsy corresponding to perfusion defect on SPECT images. In one myocardial perfusion defect at inferoposterior portion on SPECT, a non-transmural MI was found at anteroseptum. In one case with valvular disease a false positive result was obtained at posterior wall where neither myocardial necrosis nor fibrosis was observed at autopsy. This case had aortic stenosis due to bicuspid aortic valve by autopsy. The ventricle was divided into 16 segments in each of 4 short axial images to evaluate extent of MI. SPECT for extent of MI showed sensitivity of 81.9%, specificity of 96.0% and diagnostic accuracy of 92.5%. False negative segment was apt to be observed at the surrounding of non-transmural MI or basal half of left ventricle (LV) with transmural MI, while false positive segment was at posterior portion of basal half of LV. It was concluded that myocardial ECT was useful for evaluation of the site and extent of MI.

Aged↗
PubMed1986

Chronic effect of a synthetic atrial natriuretic factor on the development of hypertension in young spontaneously hypertensive rats.

The chronic effect of a synthetic atrial natriuretic factor (ANF) of 25 amino acid residues on the development of hypertension in the 6-week-old spontaneously hypertensive rat (SHR) was assessed. The SHR, on regular diets or given 1% NaCl solution for drinking, were continuously infused with ANF (150 micrograms/kg per day) or vehicle (physiological saline) as controls for up to 14 days. The ANF attenuated transiently the development of hypertension in the sodium-loaded SHR, but the blood pressure returned to control levels by day 5. In SHR on regular diets ANF did not affect the development of hypertension. In addition, ANF did not induce any significant changes in urine volume, fluid intake, urinary sodium and potassium excretion, heart rate, heart weight or haematocrit in young SHR on either normal or increased sodium intake when compared with those in vehicle-infused SHR. These results suggest that ANF may exert some role via a vascular effect at the early stage of development of hypertension in young sodium-loaded SHR.

Animals↗
PubMed1986

Hypotensive and natriuretic effects of nifedipine in essential hypertension. Role of renal kallikrein-kinin-prostaglandin and renin-angiotensin-aldosterone systems.

To assess the role of renal kallikrein-kinin-prostaglandin and renin-angiotensin-aldosterone systems in the diuretic and natriuretic actions of nifedipine, a calcium-channel blocker, 20 mg of nifedipine was administered orally to 15 patients with essential hypertension. Nifedipine promptly induced a hypotensive effect and an increase in pulse rate. Urine volume, urinary sodium excretion, and creatinine clearance were significantly increased after the administration of nifedipine by 63.5%, 48.5% and 12.4%, respectively. Urinary excretion of kallikrein and prostaglandin E were also significantly increased after the administration of nifedipine by 29.4% and 50.0%, respectively. The change in urinary kallikrein excretion was significantly correlated with that in urine volume (r = 0.70, p less than 0.01) or that in urinary sodium excretion (r = 0.86, p less than 0.01). In addition, the change in urinary prostaglandin E excretion was also significantly correlated with that in urine volume (r = 0.72, p less than 0.01) or that in urinary sodium excretion (r = 0.53, p less than 0.05). Plasma aldosterone concentration did not change despite of the marked increase in plasma renin activity, and plasma aldosterone concentration/plasma renin activity ratio decreased after the administration of nifedipine. These results suggest that the augmented renal kallikrein-kinin-prostaglandin system and the suppressed secretion of aldosterone may be associated with the diuretic and natiuretic action of nifedipine and may contribute to the reduction in blood pressure that is caused mainly by its vasodilatory action.

Adult↗
PubMed1985

Atrial natriuretic factor inhibits the hypertension induced by chronic infusion of norepinephrine in conscious rats.

To assess the physiological role of atrial natriuretic factors in the regulation of blood pressure and sodium-water excretion, we studied the chronic effects of continuous infusion of a synthetic atrial natriuretic factor of 25 amino acids for up to 3 days on systolic blood pressure, urine volume, and urinary excretion of sodium, prostaglandin E2 and kallikrein in conscious rats, and also evaluated the antihypertensive effect of this substance in rats with hypertension caused by chronic infusion of norepinephrine. Continuous infusion of atrial natriuretic factor (150 micrograms/kg per day) into the jugular vein via osmotic minipumps did not induce any changes in systolic blood pressure, urine volume, and urinary excretion of sodium, prostaglandin E2, and kallikrein for up to 3 days, compared with those in vehicle-infused rats. When the same dose of atrial natriuretic factor was administered simultaneously with 1.8 mg/kg per day of norepinephrine infused intraperitoneally by osmotic minipumps, the systolic blood pressure of conscious rats rose on day 1 to only 127.3 +/- 6.3 mm Hg compared with the rise to 146.3 +/- 1.6 mm Hg when norepinephrine alone was infused (P less than 0.05). The antihypertensive effect of atrial natriuretic factor was sustained for 3 days in rats infused with norepinephrine. The administration of atrial natriuretic factor to rats made hypertensive by 3 days of infusion with norepinephrine alone returned the blood pressure to control levels, and the antihypertensive effect was sustained throughout the experimental period lasting for 3 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗