Reno-submandibular axis controls release of extrarenal inactive renin.

The mechanisms causing the release of plasma inactive renin (PIR) area still unclear. We have investigated the role of the kidney in the release of trypsin-activable PIR from extrarenal sources in the rat, with special reference to the submandibular gland. The activation of PIR was performed by incubation with 20 mg/ml trypsin at 4 degrees C for up to 10 min; the reaction was then terminated by addition of 20 mg/ml of soybean trypsin inhibitor. Bilateral nephrectomy resulted in a gradual, marked, sex-independent increase in PIR concentration, reaching levels 4.5 times higher than basal in 24 h (time 0: 14.8 +/- 1.0 ng/ml per h; 24 h: 66.8 +/- 3.4 ng/ml per h, mean +/- s.d., P less than 0.001). This increase was not altered by the concomitant intravenous infusion of pressor doses of either angiotensin (Ang) II (30 ng/min) or pure mouse submandibular renin (a 20-ng intravenous bolus followed by intravenous infusion at the rate of 50 ng/h) for 4 h, but was completely prevented by prior removal of the submandibular glands, in which no activity of active renin and no inactive renin was detected. These results suggest that the post-nephrectomy increase of PIR is not dependent on feedback mechanisms of the suppressed renin-angiotensin system, but is controlled by the presence of submandibular glands in the rat.

Preoperative management of pheochromocytoma with the calcium-antagonist nifedipine.

Labile high blood pressure and associated complaints (eg, severe headache, palpitation, and vague discomfort in the chest) in a 28-year-old woman with pheochromocytoma were stabilized by adding nifedipine to the conventional regimen of alpha- and beta-blocking agents. Electrocardiographic (ECG) data (ST depressions, prolonged QT intervals, and giant negative T waves during a hypertensive attack) and findings in biopsied myocardial specimens (slight cell infiltration composed mainly of lymphocytes associated with interstitial fibrosis) had suggested the presence of catecholamine cardiomyopathy. Oral administration of 10 mg of nifedipine alone had rapidly resulted in normalization of blood pressure and complete relief from associated signs and symptoms. Because conventional preoperative treatment with alpha- and beta-blockers did not alleviate the hypertensive attacks, a 20-mg long-acting nifedipine tablet was added to the regimen. The effect of twice-daily administration of a 20-mg long-acting nifedipine tablet (combined with alpha- and beta-blockers) was so prominent that it was possible for the patient to undergo surgery for removal of the right adrenal gland and a 4-cm tumor at the gland. After surgery there were no abnormal ECG findings.

Increased furosemide-sensitive sodium influx into erythrocytes in non-insulin-dependent diabetes mellitus associated with hypertension.

Our previous study demonstrated increased sodium (Na+) influx into ouabain-treated erythrocytes in diabetic patients with hypertension. The present study was designed to estimate the effect of furosemide on the Na+ influx in non-insulin-dependent diabetes mellitus (NIDDM) with hypertension. Both Na+ influx in the absence of furosemide (total Na+ influx; TNaI) and furosemide-sensitive Na+ influx (FSNaI) were increased in patients with essential hypertension (group 1, n = 22) than those in non-diabetic, normotensive control subjects without family history of hypertension (control group, n = 26, P less than 0.001 and P less than 0.001, respectively). TNaI and FSNaI in diabetic patients without hypertension (group 2, n = 28) were also higher than those in the control group (P less than 0.02 and P less than 0.001, respectively), but no significant differences were found in TNaI or FSNaI between groups 1 and 2. TNaI and FSNaI in diabetic patients with hypertension (group 3, n = 19) were elevated than those in control group (P less than 0.001 and P less than 0.001, respectively), in group 1 (P less than 0.05 and P less than 0.02, respectively) and in group 2 (P less than 0.001 and P less than 0.001, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Electrophysiological diagnosis of participation of accessory pathway in patients with paroxysmal supraventricular tachycardia.

Electrophysiological studies were performed on 34 patients whose reentrant circuit of paroxysmal supraventricular tachycardia (PSVT) involved normal atrioventricular (AV) conduction system as the antegrade limb and either overt (25 patients) or concealed (9 patients) accessory AV pathway as the retrograde limb. The diagnosis of this mechanism was made by one or more of the following: 1) eccentric retrograde atrial activation sequence; 2) effect of bundle branch block on ventriculoatrial (VA) conduction time; 3) paradoxically premature atrial capture; 4) atrial capture by premature ventricular stimulation of VA conduction time with retrograde during PSVT; 5) no significant prolongation of VA conduction time with retrograde atrial activation sequence to that of PSVT during incremental and premature ventricular stimulation; 6) shortening of cycle length with constant H-V and V-A intervals after atropine administration. The participation of accessory pathway in PSVT circuit should be decided by as many of the above-mentioned findings or procedures as possible for optimal therapy. Electrophysiological studies have led to the recognition that accessory pathway, functionally silent during antegrade conduction, is responsible for some patients with PSVT. If the mechanisms of PSVT were more carefully analyzed, the recognition of PSVT cases involving accessory pathway would increase.

[Roles of kidney and submandibular gland in the release of rat plasma inactive renin].

In this study we outlined the development of an enzymatic technique to activate plasma inactive renin by trypsin in rat plasma. Using this method, we reported the releasing mechanism of the trypsin-activable inactive renin which has not yet been clarified. Adult male Wistar rats (260-300 g) were kept on regular diet (Na: 260 mg/100g) unless explained and underwent operation under pentobarbital anesthesia (50 mg/kg). Blood samples were obtained from conscious rats through the cannulae, which had been inserted into the left femoral arteries 24h before the experiments. After addition of excessive renin substrate which had been obtained from the 24 h-nephrectomized rat plasma, renin was measured by the commercial RIA-kit (Dainabot). Trypsin (Worthington) treatment (20 mg/ml plasma for 10 min at 4 degrees C) was followed by addition of SBTI (Sigma) (20 mg/ml plasma). This condition maximally increased the rate of angiotensin I generation and did not alter the Km or optimum pH of the renin reaction. In this condition, trypsin reaction was completely inhibited by adding these concentrations of SBTI. The molecular weight of inactive renin (51,000) in the normal rat plasma estimated by Sephadex G-100 column (Pharmacia) was the same as that in the nephrectomized rat plasma. In conclusion, trypsin treatment of plasma (20 mg/ml plasma for 10 min at 4 degrees C) followed by SBTI (20 mg/ml plasma) was justified for trypsin activation of rat plasma. Using this method, we investigated the changes in active and inactive renin after bilateral nephrectomy in the salt-depleted rat. Active renin decreased rapidly after bilateral nephrectomy with a half life of 23.6 +/- 4.0 min. Inactive renin, on the other hand, increased gradually and reached to a plateau 24 h after bilateral nephrectomy, and was kept unchanged during the following 24 h. The infusion of mouse submandibular gland active renin or angiotensin II could not prevent the increase of plasma inactive renin in the nephrectomized rat. These suggest that there may be no feedback mechanisms between plasma inactive and active renin or angiotensin II. Furthermore, we investigated the organ-related sources of plasma inactive renin which markedly increased after total nephrectomy. Simultaneous removals of submandibular glands but not of adrenal glands completely prevented the postnephrectomy increases of plasma inactive renin. But, removals of submandibular glands or adrenal glands alone were followed by no changes in the basal levels of plasma inactive renin.(ABSTRACT TRUNCATED AT 400 WORDS)

Increased sodium influx into erythrocytes in diabetes mellitus and hypertension.

A variety of abnormality has been reported in the cation transport systems in erythrocytes in essential hypertension. To determine the existence of similar abnormality in diabetics with hypertension, sodium (Na+) influx into erythrocytes in the presence of ouabain (measured by using 22Na+), and the Na+ and potassium (K+) content in intact erythrocytes were examined. Subjects, all of whom were Japanese, were divided into 4 groups; 23 nondiabetic, normotensive control subjects without family history of hypertension (control group), 20 patients with essential hypertension (group 1), 21 normotensive diabetics without family history of hypertension (group 2) and 15 hypertensive diabetics (group 3). Na+-K+ pump activity (measured by using 86Rb+) was studied in some of them, too. Na+ influx in group 1 was 0.451 +/- 0.111 m mol/Kg erythrocytes/h, significantly more elevated than that in the control group (0.345 +/- 0.080, p less than 0.001). Na+ influx in group 2 (0.435 +/- 0.094) was significantly greater than that in the control group (p less than 0.005), but no significant difference was found between groups 1 and 2. Na+ influx in group 3 (0.551 +/- 0.128) was significantly higher than that in the control group (p less than 0.001), in group 1 (p less than 0.02), or in group 2 (p less than 0.005). There were no significant differences in Na+-K+ pump activity, or Na+ and K+ content among the 4 groups. These findings suggested that: Na+ influx into ouabain-treated erythrocytes was higher in patients with essential hypertension than in control subjects in Japanese, diabetes mellitus per se might increase Na+ influx, and the elevation of blood pressure in hypertensive diabetics as well as in essential hypertensives might be related to the increased Na+ influx.

The hypotensive effect of single-dose captopril in diabetics.

To determine the role of the kallikrein-kinin (KK) system in patients with diabetes mellitus in relation to nephropathy and/or hypertension, the single-dose effects of captopril (25 mg, p.o.) were examined in 9 control subjects and 32 diabetics (group 1; 11 normotensives without nephropathy, group 2;10 hypertensives without nephropathy, group 3; 11 hypertensives with nephropathy). Significant hypotensive effects of captopril were found in groups 1 and 2 as well as in the control group, but not in group 3. These hypotensive effects were completely blocked by the infusion of ethyl-p-(6-guanidinohexanoyloxy) benzoate methanesulfonate (FOY), a kallikrein inhibitor. The administration of captopril during vehicle infusion induced a significant elevation of plasma renin activity (PRA) at 60 and 120 min after captopril in each group, except for group 3. FOY cancelled these captopril-induced effects on PRA in those groups. No correlation was found between pretreatment PRA and the changes in mean blood pressure (MBP) after captopril during vehicle infusion in whole diabetics. In addition, the daily urinary excretion of kallikrein in group 3 was significantly lower than that in groups 1 and 2 as well as in the control group. These results suggest that the hypotensive action of captopril in diabetics without nephropathy may be largely due to activating the KK system, and that the KK system may be suppressed in hypertensive diabetics with nephropathy.

[Role of the submandibular glands in in vivo mechanisms of plasma inactive renin release in the rat].

In our present studies, we evaluated the role of the submandibular glands (SMG) on plasma inactive renin (PIR) releasing mechanisms in rats using some agents which are known to stimulate plasma active renin (PAR) release. The results were analyzed between sialoadenectomized (SX) and sham-operated (control: C) rats. Twenty-four h after the operation, PAR releasing agents, furosemide (FRO) 2.5 mg/rat/h with prior iv bolus 5 mg, captopril (CAP) 5 mg/rat/h with prior iv bolus 10 mg, 1-Sar-8-Ile-angiotensin II (Ang II A) 300 ng/kg/min, prostaglandin E1 (PGE1) 100 ng/kg/min, and prostaglandin I2 (PGI2) 100 ng/kg/min, were infused through femoral venous cannulae. Blood samples were taken through femoral arterial cannulae into test tubes containing 2 mg EDTA-2Na. PAR was assayed by RIA, and total renin was obtained after tryptic activation. According to the responses of PIR, the agents used were categorized into three patterns: FRO increased PIR, both PGs lowered PIR, and, CAP and Ang II A had no effect on PIR release. The PIR release mechanisms by FRO were further investigated by 20 mg FRO ip injection in totally nephrectomized rats. PIR increased even in nephrectomized rats, but the increase was totally canceled by the following SX. In conclusion, FRO alone among some agents studied is able to stimulate PIR release only under the existence of SMG.

[Roles of the kidney in activation and release of plasma inactive renin in the rat].

Plasma inactive as well as active renin is supposed to originate from the kidney, though there is little direct evidence. As we have previously reported (Sakanaka et al., Folia Endocrinol. Jap., 63: 961-977, 1987; Miyazaki et al., J. Hypertension 4 (Suppl 6): S453-S455, 1986; Miyazaki et al., J. Hypertension 6: 33-40, 1988), the submandibular gland, but not the kidney, is thought to play an crucial role in releasing plasma inactive renin in the rat. In the present acute studies, we attempted to elucidate the roles of the kidney in the release mechanisms of plasma inactive renin. Adult male rats maintained on a regular rat chow (Na: 260 mg/100g) were uninephrectomized, and vessel clips were placed on the renal pedicles of the contralateral kidneys to make completely ischemic and non-filtered kidneys. In the first protocol, the renal pedicles were occluded for 2 h, followed by the removal of the vessel clips. During the occlusion for 2 h, plasma active renin concentration (PAC) in the peripheral blood obtained from the femoral cannulae decreased, while plasma inactive renin concentration (PIC) along with plasma total renin concentration (PTC) increased as in the case of total nephrectomy, which supports our previous studies. Then, declipping resulted in the rapid rise in PAC with the peak values at 2 min, which was followed by its gradual decrease with time during the experimental period (30 min). On the other hand, PIC decreased gradually toward control levels with no rise after declipping. In the second protocol, blood trapped in the kidney was collected through the renal venous cannulae at 0, 60, 120 and 240 min after the pedicle occlusion in the different groups of rats. The renal blood levels of PAC increased by more than three times at 240 min compared to the control values, while PIC decreased to one third of the control values. PTC increased at 120 and 240 min. Renal tissue levels of renin were also measured at 0 and 120 min in the second protocol in the kidneys of rats which were maintained on a regular rat chow. Inactive renin concentration increased, while active renin concentration decreased. These were compatible with the results obtained in plasma. In the last protocol, the second protocol was in part repeated in salt-depleted rats which were kept on a low salt diet (Na: 11.3 mg/100g) for 2 weeks.(ABSTRACT TRUNCATED AT 400 WORDS)

[Release mechanisms of inactive renin from rat renal cortical slices: role of the submandibular gland].

In our previous studies, we showed an in vivo stimulating effect of the extract of the rat submandibular gland on plasma inactive renin release. In this study, we evaluated the effects of the rat submandibular gland extract and of some plasma active renin stimulants on inactive renin release from rat renal cortical slices. Adult male Wistar rats (250-350g) were kept on a regular diet (Na 260mg/100g) and nephrectomized under pentobarbital anesthesia (50mg/kg, i.p.). Five thin renal cortical slices were obtained from each kidney by using a razor blade. These renal cortical slices were incubated in Earle's buffer (pH7.4, Difco) at 37 degrees C for 30 min (preincubation), then transferred into 10ml fresh Earle's buffer with or without some agents and incubated at 37 degrees C for 1 hour (experimental incubation). For each experiment, 6 groups of 5 renal cortical slices were employed. The agents used in this study were as follows: isoproterenol (10(-5)M), furosemide (50 micrograms/ml), prostaglandin E1 (10(-5)M), prostaglandin I2 (10(-5)M) and the rat submandibular gland extract (100 microliters) which was obtained after homogenation with 10 x (w/v) 0.01M pyrophosphate buffer (pH6.5) including 0.1M NaCl. One ml of samples of this Earle's buffer were withdrawn every 20 min. Active renin in the samples was assayed by the commercial RIA-kit (Dainabot), and total renin was assayed after trypsin (Worthington) treatment (30 micrograms/300 microliters sample) at 4 degrees C for 10 min. Inactive renin was determined as the difference between total renin and active renin. Active and inactive renins increased linearly in the buffer without any agents (control) during the observation period (60 min). Isoproterenol (10(-5)M) stimulated the release of active renin significantly (p less than 0.01 vs. control) but did not affect the release of inactive renin. Furosemide (50 micrograms/ml) stimulated the release of active and inactive renins significantly at 20 and 40 min (p less than 0.05 vs. control) but did not affect the release of either renin at 60 min. Both prostaglandins E1 and I2 (10(-5)M) stimulated the release of active renin significantly (p less than 0.01 vs. control) but inhibited, on the other hand, the release of inactive renin significantly (p less than 0.01 vs. control). The rat submandibular gland extract (100 microliters) did not affect the release of active renin but stimulated the release of inactive renin significantly (p less than 0.05 vs. control).(ABSTRACT TRUNCATED AT 400 WORDS)

The significance of autonomic neuropathy in the elevation of inactive renin in diabetes mellitus.

Plasma renin activity (PRA) and inactive renin(IR, activated by trypsin) were measured in the plasma of 15 type II diabetics with autonomic neuropathy (group 3), 15 type II diabetics without (group 2), and 14 nondiabetic control subjects (group 1) in the recumbent position. There were no significant differences between the 3 groups with respect to age, ideal body weight, supine resting mean blood pressure, serum creatinine, daily urinary excretion of sodium, or renin substrate at the time of study. Autonomic neuropathy (AN) was assessed by measurement of the ratio of the longest to the shortest R-R interval during deep breathing (E/I-ratio) and by postural hypotension. PRA was significantly lower in group 3 than in group 1 (p less than 0.05). The IR level was significantly higher in group 3 than in groups 2 and 1 (p less than 0.005 for both comparisons). The ratio of active renin to total renin (TR) (PRA/(IR + PRA)) was significantly lower in group 3 than in groups 2 and 1 (p less than 0.001 for both comparisons). The IR level and PRA/(IR + PRA) were significantly correlated with E/I-ratio (r = -0.498, p less than 0.01 and r = 0.588, p less than 0.001, respectively) and with the severity of postural hypotension (r = 0.383, p less than 0.05 and r = 0.401, p less than 0.05, respectively), but not with the daily urinary excretion of protein or 24 h-creatinine clearance (24 h-Ccr) in the whole diabetics. From these results, we conclude that autonomic neuropathy might be a more important factor than nephropathy in the lower PRA and higher IR level in type II diabetics with AN.

A case of progressive systemic sclerosis (PSS) with silent thyroiditis and anti-bovine thyrotropin antibodies.

We have examined a patient with progressive systemic sclerosis (PSS) who had increased serum T3 (235 ng/dl) and T4 (13.2 micrograms/dl) and low 24-h thyroidal 123I-uptake (1.2%). A diagnosis of silent thyroiditis was made on the basis of the clinical course and laboratory and histopathologic findings. Simultaneous measurement of serum anti-thyrotropin receptor antibody (TRAb) showed a negative value (-49.0%) which suggested the presence of anti-TSH antibody. Further examination by immune precipitation with 125I-bovine TSH (bTSH) and also with 125I-human TSH (hTSH) revealed the presence of anti-bTSH antibody but not anti-hTSH antibody in his serum gamma-globulin. The significance of the association of PSS, silent thyroiditis, and anti-bTSH in one individual is discussed.

[Image diagnosis of adrenal disorders--I. CT images of control subjects and image diagnosis of primary aldosteronism].

The shape and size of the adrenals in control subjects without adrenal disorders were studied by computed tomography (CT), and a comparative assessment of diagnostic values of ultrasonography (US) by electronic linear scanner, CT, and adrenal scintigraphy was made on 9 patients with primary aldosteronism. Adrenal imaging by scintigraphy was performed on the 5th and 6th day, or further on the 7th day after the injection of 1 mCi of Adosterol. CT findings of the adrenals in control subjects: Eighty-two % of 100 control right adrenals, and 89% of 100 control left adrenals were detected by CT. Seventy-seven % of the right adrenals were in linear-shape, and the others were in V-shape. The shape of the left adrenals could be classified into triangular-shape (54%), Y-shape (28%) and V-shape (18%). The mean width and thickness of the right adrenals were 28.6 +/- 7.5 mm (M +/- SD) and 3.8 +/- 1.4 mm, respectively. Those of the left ones were 19.4 +/- 5.5 mm and 5.3 +/- 1.8 mm. Image diagnosis of primary aldosteronism: In 2 out of 3 patients examined by US, aldosteronomas were detected. In these 2 patients, one had 2 adenomas 2.8 X 1.7 X 1.2 cm and 1.0 X 1.0 X 2.0 cm in size, and the other had one adenoma 0.8 X 1.0 X 2.0 cm in size. On adrenal scintiscanning under dexamethasone pretreatment (DP), the isotope uptake of aldosteronoma was still seen with the disappearance of the contralateral adrenal in 7 out of 9 cases. In these 7 cases, the laterality of the tumor was confirmed. In one of the remaining 2 cases, the bilateral adrenal images were obtained regardless of DP. In the other case, of which aldosteronoma was the smallest (0.6 X 0.6 X 0.8 cm), the image of the affected adrenal with adenoma as well as the contralateral adrenal disappeared under DP. CT delineated all aldosteronomas in 8 cases examined including 2 cases in which adrenal scintiscanning failed to elucidate the localization of aldosteronoma. These results indicated that the combination of these 3 new image diagnostic methods was available for the detection of aldosteronomas of various sizes.