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Biomedical subjects

M Kanazawa

Publications and source records attributed to M Kanazawa.

At least 271 records · Page 15Linked to original sources
PubMed1988

Cyclic GMP accumulation by atriopeptins in cultured rat renal and vascular smooth muscle cells.

To evaluate the role of cyclic guanosine monophosphate (cGMP) in the vascular and renal action of atrial natriuretic peptide (ANP), we compared the effects of atriopeptins (APs) on cGMP accumulation in cultured cells from rat mesenteric vascular smooth muscle (VSM), glomerular mesangium (GM) and renal papillary collecting tubule (RPCT), and also evaluated the relationship between renal sodium or water excretion and urinary cGMP in AP-infused rats. Both AP I and AP III increased intracellular cGMP levels dose-dependently in all types of cells, while they did not affect intracellular cAMP levels or prostaglandin synthesis. AP III was 100 times more potent than AP I. The magnitude change in cGMP levels was largest in GM cells. The sensitivity of VSM and GM cells to AP III were greater than that of RPCT cells. There were significant positive relationships between urinary excretion of sodium or water and that of cGMP levels in AP-infused rats. These results may suggest that GM and VSM cells are the principal targets for ANP to stimulate cGMP synthesis and, possibly, to exert the renal sodium and water excretion, and also support the hypothesis that cGMP mediates the cellular action of ANP.

Animals↗
PubMed1987

The degree of increment in plasma catecholamines in patients with mitral stenosis by mild exercise.

Although sympathetic excitation during mild exercise may readily occur in patients with mitral stenosis (MS), the degree of increment in plasma catecholamines has not been fully investigated. We imposed mild ergometric exercise (50 watts, 300 kg/min for 5 minutes) on five patients with mild MS (mitral valve area greater than or equal to 1.0 cm2) and eight with severe MS (mitral valve area less than 1.0 cm2) while they were undergoing cardiac catheterization. In patients with severe MS, total plasma catecholamine levels during exercise were remarkably higher (2821 +/- 783 [SEM] pg/ml) than in those with mild MS (957 +/- 113 pg/ml, p less than 0.05) and in seven control subjects (612 +/- 75 pg/ml, p less than 0.05). This marked increment could not be predicted by heart rate response, which did not differ between severe and mild MS (166 +/- 5 vs 153 +/- 10 bpm). In contrast with catecholamine change, the cardiac index in severe MS showed a very small increment. Results suggest that mild daily exercise can remarkably increase plasma catecholamine levels in severe MS, and this may accelerate various complications of this disorder.

Adult↗
PubMed1987

Renal kallikrein activity in spontaneously hypertensive rats.

To assess possible roles of the renal kallikrein-kinin system in the development of spontaneous hypertension, we determined daily excretion of urinary total and active kallikrein in 6-week-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats for up to 2 weeks. We also evaluated the effect of aprotinin, a reversible inhibitor of kallikrein and other serine proteases, on the development of hypertension in the 6-week-old SHR on ordinary intakes of sodium or on sodium loading with 1% NaCl for up to 2 weeks. Active kallikrein was determined by its kininogenase activity, and the generated kinins were radio-immunologically measured. Total kallikrein was also determined by measuring kininogenase activity after inactive kallikrein had been activated with trypsin (200 micrograms/ml). Urinary active kallikrein excretion was significantly reduced in 7-week-old SHR (1.5 +/- 0.2 microgram/day compared to 2.8 +/- 0.3 micrograms/day in WKY, P less than 0.05) and in 8-week-old SHR (1.6 +/- 0.2 microgram/day compared to 3.2 +/- 0.4 micrograms/day in WKY, P less than 0.01). Urinary total kallikrein excretion was also reduced in the 7- and 8-week-old SHR whereas the ratio of active to total kallikrein did not change. In addition, renal contents of total and active kallikrein were significantly lower in the 8-week-old SHR than in the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Long-term effects of aldosterone on kallikrein, prostaglandin E2 and sodium in rats.

To assess the long-term effects of mineralocorticoids on the regulation of the synthesis or release of kallikrein and prostaglandin E2 in the renal kallikrein-kinin-prostaglandin E system, we studied the effects of chronic infusion of aldosterone (50 micrograms/kg/day) on urinary excretion of total and active kallikrein, and prostaglandin E2 for 10 days in conscious rats on regular intakes of sodium and on sodium loading with 1% NaCl as a drinking water. Chronic infusion of aldosterone induced a prompt and transient decrease in the ratio of sodium to potassium and a sustained increase in urinary prostaglandin E2 excretion in rats on regular diets, whereas urinary total and active kallikrein excretion did not increase significantly until the 4th day of aldosterone infusion. In rats loaded with sodium, aldosterone did not induce any changes in urinary total and active kallikrein excretion, whereas it induced similar changes in the ratio of sodium to potassium and urinary prostaglandin E2 excretion to those in rats on regular diets. Thus, the present results suggest that aldosterone might stimulate the synthesis or release of renal prostaglandin E2 independent of sodium balance. Furthermore, it is also suggested that aldosterone might stimulate the synthesis or release of kallikrein, at least partly, via the same pathway as sodium loading does.

Aldosterone↗
PubMed1987

No evidence on significant roles of the prostaglandin-thromboxane and kallikrein-kinin system in the antihypertensive effect of MK 421 in rats made hypertensive by norepinephrine or vasopressin.

Inhibition of angiotensin converting enzyme by MK 421 (6 mg/kg/day ip) induced a significant increase in urinary kinin excretion in norepinephrine-infused rats (1.8 mg/kg/day ip), whereas it had no effect on urinary prostaglandin E2 excretion. In contrast, MK 421 did not induced any significant changes in urinary kinin and prostaglandin E2 excretion in vasopressin-infused rats (7.2 U/kg/day ip). The simultaneous administration of indomethacin (10 mg/kg/day sc), OKY 046 (12 mg/kg/day sc) or aprotinin (100,000 units/kg/day sc) did not affect the antihypertensive effect of MK 421 in rats made hypertensive by chronic infusion of norepinephrine or vasopressin. The present results suggest that the hypotensive effect of MK 421 may depend on a reduced sensitivity of the vasculature to vasoconstrictor substances. In addition, it is also suggested that neither the prostaglandin-thromboxane or kallikrein-kinin systems are essential for the antihypertensive effect of MK 421 in these models of hypertension.

Animals↗
PubMed1987

Effects of angiotensin converting enzyme inhibitors MK 421, SA 446 and captopril on renal prostaglandin E and kinins in conscious normotensive rats.

Angiotensin converting enzyme inhibition by MK 421, SA 446 or captopril (6 mg/kg/day ip) for up to 6 days induced significant fall in systolic blood pressure and plasma angiotensin II concentration. The hypotensive effect was greater in sodium depleted rats than in sodium repleted rats. The hypotensive effect was also accompanied by increased excretion of urinary prostaglandin E2, however the levels of urinary prostaglandin E2 in sodium repleted rats were not different from those in sodium depleted rats. Urinary kinin excretion was increased during infusion of MK 421, SA 446 or captopril in sodium depleted rats, whereas no significant change was found in sodium repleted rats. Thus the present results suggest that renal prostaglandin E system may not be essential for the hypotensive effect of these inhibitors. In addition, the greater hypotensive effect of these inhibitors in sodium depleted rats may be in part due to stimulated renal kinin system.

3-Mercaptopropionic Acid↗
PubMed1984

Lack of effect of cyclandelate in peripheral arterial disease.

While cyclandelate is widely used in the therapy of peripheral arterial disease, objective evidence of its efficacy remains controversial. For this reason, 12 patients with intermittent claudication (average age of 66.8 years) received both cyclandelate 400 mg qid and placebo in a double-blind crossover trial lasting two months. During the cyclandelate and placebo periods, the following peripheral hemodynamic measurements were obtained using a plethysmograph and treadmill claudication testing: mean calf blood flow, vascular resistance and venous capacitance; finger and toe blood flow, pulsation amplitude and temperature before and after vasodilating maneuvers; arm and leg arterial pulsation amplitudes, one and ten minute calf reactive hyperemia reaction; 30 pound/30 second calf active hyperemia reactions and times of onset of claudication as measured on a treadmill. No major significant difference could be demonstrated between placebo and cyclandelate on any subjective symptom or any objective measurement. It is concluded that cyclandelate 400 mg qid for 4 weeks was of little objective value in treating this group of 12 patients with peripheral arterial disease and suffering from intermittent claudication.

Aged↗