Masato Matsunaga

Detection of low molecular kininogen messenger RNA in human kidney.

The purpose of the present study was to confirm expression of kininogen in human kidneys. As the human kininogen gene is alternatively transcribed to high molecular weight and low molecular weight kininogen messenger (m)RNA, we constructed a probe which can discern these two transcripts by the S1 nuclease mapping analysis. The low molecular weight kininogen mRNA was detected in human kidney cortex and medulla. This finding strongly supports the existence of a local kinin-kallikrein system in human kidneys.

PRODUCTION AND RELEASE OF INACTIVE RENIN BY HUMAN VASCULAR SMOOTH MUSCLE CELLS

Human arterial smooth muscle cells were obtained from surgically excised tissues and cultured by the explant method. The cultured cells had both active and inactive forms of an angiotensin I forming enzyme. About a five-fold increase in the activity was obtained by trypsin treatment. This renin-like enzyme was also found in abundance in the culture media, mostly in an inactive form. Most of the enzyme activity, either before or after the activation, was suppressed by an antibody specific to human renin. The inactive enzyme was activated to some extent also by acidification and by cold exposure. The molecular weight of the inactive enzyme was estimated to be approximately 49,000 by gel filtration. These results suggest that human vascular smooth muscle cells can produce renin and release an inactive form of renin, and can be a potential source of plasma inactive renin under certain conditions such as the anephric state.

A case of 17α-hydroxylase deficiency syndrome associated with right adrenal tumor

A 35-year-old woman, who had been hypertensive for about 17 years and had lacked menarche, showed hypokalemia, low plasma cortisol and aldosterone levels, suppressed renin activity, and marked elevation of plasma corticosterone. The patient was diagnosed as having 17 alpha-hydroxylase deficiency from functional studies. In addition, a right adrenal tumor was found by adrenal venography. Adrenal venous sampling showed that this tumor might be secreting corticosterone and possibly also deoxycorticosterone (DOC). The genotype was 46,XY, so she was diagnosed as having male pseudohermaphroditism. Right adrenalectomy and contralateral adrenal biopsy were done. The retained testicles were removed. Dexamethasone administration normalized the blood pressure and serum potassium. This is the first report of 17 alpha-hydroxylase deficiency with a right adrenal tumor.

Reexamination of the conditions for processing and storing of blood for plasma renin assay

Reexamination of conditions for processing and storing blood for plasma renin assay confirmed that plasma can be stored at -20 degrees C for at least 4 weeks without significant changes in active renin level. The active renin concentration is increased by storage at 4 degrees C because of conversion from inactive renin.

The effects of nifedipine and captopril on renal function in patients with essential hypertension: comparison with sodium nitroprusside.

In comparison with a nonspecific vasodilator, sodium nitroprusside (SNP), we intended to deduce the characteristics of nifedipine (NIF) and captopril (CAP) in the treatment of hypertension. Ten patients with essential hypertension were hospitalized and kept on a constant sodium diet (10 g NaCl/day). Renal blood flow (RBF) and glomerular filtration rate (GFR) were measured before and after the respective administration of SNP (0.9 +/- 0.5 mcg/kg/min), NIF (17 +/- 5 mg), and CAP (85 +/- 24 mg). SNP significantly reduced the mean blood pressure (MBP), the renal vascular resistance index (RVRI), urine volume (UV), urinary excretion of sodium (UNaV), and significantly raised active renin concentration (ARC), plasma norepinephrine (NE), and the heart rate (HR). RBF, GFR, and plasma epinephrine (E) were not changed. Compared with SNP, NIF significantly raised RBF, UV, UNaV, and fractional excretion of sodium (FENa) and significantly reduced RVRI. The differences between the increases in ARC, NE, and HR by NIF and those by SNP were not significant. GFR and E were not changed by NIF. Although CAP did not reduce MBP as much as SNP did, the increase in RBF by CAP was significantly greater than that by SNP. Changes in GFR, UV, UNaV, FENa, and E by CAP were not different than those by SNP. CAP increased ARC and did not raise E, NE, and HR. In conclusion, compared with SNP, NIF significantly raised RBF, UV, UNaV, and FENa and significantly reduced RVRI. On the other hand, the renal response to CAP was not very much different from the response to SNP. The characteristics of CAP were the suppressed sympathetic response to the decrease in blood pressure.

Regulated expression of human atrial natriuretic polypeptide gene in mouse L cells.

To investigate whether the human atrial natriuretic polypeptide (hANP) gene is responsive to glucocorticoid, we co-introduced the hANP gene (with SV40 enhancer) with HSV-tk gene into mouse tk- L cells. The transformants with hANP gene with SV40 enhancer expressed hANP specific RNAs. The administration of 1 microM dexamethasone reduced the expressed hANP specific RNAs, especially those that had a physiological initiation site. These results suggest that the hANP gene is really a glucocorticoid responsive gene and may be negatively regulated by glucocorticoid.

Expression of human atrial natriuretic polypeptide gene in cos 7 cells

Cos 7 cells transfected with human atrial natriuretic polypeptide (hANP) gene with SV40 enhancer and replication origin sequences expressed hANP gene. The expressed RNA was indistinguishable from native hANP mRNA and the transcribed protein seemed to be properly processed to alpha-hANP and beta-hANP. This system provides a useful approach to investigate the processing of hANPs and the structure-function relationship of amino acid sequences of hANPs.

DYNAMIC CHANGES IN PLASMA INACTIVE RENIN LEVELS IN BARTTER'S SYNDROME AFTER ADMINISTRATION OF CAPTOPRIL AND ANGIOTENSIN II

1. Changes in plasma active and inactive renin concentration (ARC and IRC) after captopril administration and angiotensin II (AII) infusion were studied in six patients with Bartters syndrome.

Effects of Enalapril Maleate on Plasma Level of Inactive Renin in Renovascular Hypertension

Changes in plasma levels of active and inactive renin after the treatment with enalapril maleate (MK-421), a new angiotensin converting enzyme inhibitor, were studied in five patients with renovascular hypertension (RVH) due to unilateral renal artery stenosis. The dosage was increased when the blood pressure (BP) was not normalized for more than 3 days. Blood sampling was performed before, and 5 hours and 24 hours after the first administration, and on the 3rd day with each dosage. Active and inactive renin concentrations (ARC and IRC) showed a reciprocal change in 4 cases, 5 hours after the first dose. In the chronic treatment, ARC and IRC before the morning dose did not change apparently until the BP was normalized, when both ARC and IRC were evidently increased. It was suspected that a conversion from inactive to active renin may occur in the patients with RVH, when the active renin secretion is stimulated suddenly by the first dose of MK-421. The chronically diminished perfusion pressure in the kidney may stimulate the secretion of inactive renin, but the decrease in endogenous angiotensin II may not.

Studies on the Active and Inactive Renin in Renovascular Hypertension

Active and inactive plasma renin concentrations (ARC and IRC) from both renal veins and the femoral artery, and the molecular weight (MW) of active and inactive renin (AR and IR) from both renal veins were measured in 6 patients with renovascular hypertension due to unilateral renal artery stenosis. Venous ARC on the affected side was higher than that on the unaffected side and arterial ARC. In 4 patients ARC increased and IRC decreased after circulating through the stenotic kidney, while in the other 2 cases venous IRC on the stenotic side was higher than arterial IRC. The MW of AR on the stenotic and non-stenotic sides were 40000-48000 and 45000-48000, respectively, and those of IR varied from 45000-53000 and 48000-55000, respectively. These values seem to be smaller than those of normal subjects. The renin molecule may be small immediately after the release from the kidney and become larger in the circulation. In 3 cases, whose ARC increased and IRC decreased after passing through the stenotic kidney, AR and IR from the stenotic kidney were smaller than those from the non-stenotic kidney. Some mechanism of AR and IR molecule reduction may work in the stenotic kidney to activate IR.