Detection of dihydropyridine- and voltage-sensitive intracellular Ca(2+) signals in normal human parathyroid cells.

We recently showed dihydropyridine- and voltage-sensitive Ca(2+) entry in cultured parathyroid cells from patients with secondary hyperparathyroidism. To determine whether normal parathyroid cells have a similar extracellular Ca(2+) entry system, cells were isolated from normal (non-hyperplastic) human parathyroid glands. Fluorescence signals related to the cytoplasmic Ca(2+) concentration ([Ca(2+)]I) were examined in these cells. Cells loaded with fluo-3/AM showed a transient increase in fluorescence (Ca(2+) transient) following a 10-s exposure to a 150 mM K(+) solution in the presence of millimolar concentrations of external Ca(2+). The Ca(2+) transient was reduced by dihydropyridine antagonists or 0.5 mM Cd(2+), but enhanced by FPL-64176, an L-type Ca(2+)-channel agonist. Ca(2+) transients induced by the 10-s exposure to 3.0 mM extracellular Ca(2+) ([Ca(2+)]o) were also inhibited by dihydropyridine antagonists or 0.5 mM Cd(2+). These results provide the first evidence that normal human parathyroid cells express a dihydropyridine-sensitive Ca(2+) entry system that may be involved in the [Ca(2+)]o-induced change in [Ca(2+)]I. This system might provide a compensatory pathway for negative feedback regulation of parathyroid hormone secretion under physiological conditions.

Low-grade endotoxemia contributes to chronic inflammation in hemodialysis patients: examination with a novel lipopolysaccharide detection method.

Chronic inflammation has recently been proposed to play a major role in the development of cardiovascular disease and mortality among advanced chronic kidney disease (CKD) patients; however, why advanced CKD promotes chronic inflammation is still unclear. We hypothesized that a very low level of plasma endotoxin (lipopolysaccharide [LPS]) contributes to chronic inflammation in advanced CKD patients. We measured the plasma LPS levels using a novel LPS detection method (ESP method, a method for endotoxin detection using laser scattering photometry) concurrently with serum C-reactive protein (CRP) levels and various blood tests in 17 stable hemodialysis (HD) patients. As a result, the median LPS levels measured by the ESP method was 0.23 pg/mL (range, 0.01-3.89) (inflow, start of HD), 0.22 pg/mL (<0.01-9.97) (outflow, start of HD), 0.37 pg/mL (<0.01-7.42) (inflow, end of HD), and 1.07 pg/mL (<0.01-10.66) (dialysate), respectively; statistically significant differences were not detected between them. The predialysis median CRP level was 0.19 mg/dL (0.04-3.02). The logarithm of plasma LPS independently correlated with serum CRP (R = 0.595, P = 0.0103). In multiple (forward stepwise) regression analysis, in which CRP was determined to be the criterion variable, LPS (log), albumin, and the white blood cell count were adopted as independent explanatory variables (R = 0.401, -0.397 and 0.387, respectively). In conclusion, the present study revealed a significant relationship between LPS and CRP using the novel ESP method, and suggested that very low-grade endotoxemia is contributing to systemic inflammation in HD patients.

Dihydropyridine- and voltage-sensitive Ca2+ entry in human parathyroid cells.

Patch-clamp and fluorescence measurements of cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) were performed to directly detect extracellular Ca(2+) entry into cultured parathyroid cells from patients with secondary hyperparathyroidism. Cells loaded with fluo-3 AM or fluo-4 AM showed a transient increase in fluorescence (Ca(2+) transient) following 10 s exposure to 150 mm K(+) solution in the presence of millimolar concentrations of external Ca(2+). The Ca(2+) transient was completely inactivated after 30-40 s exposure to the high-K(+) solution, was reduced by dihydropyridine antagonists and was enhanced by FPL-64176, an L-type Ca(2+) channel agonist. The electrophysiological and pharmacological properties of the whole-cell Ca(2+) and Ba(2+) currents were similar to those of L-type Ca(2+) channels. The Ca(2+) transients induced by 10 s exposure to 3.0 mm extracellular Ca(2+) concentration ([Ca(2+)](o)) were inhibited by dihydropyridine antagonists and were partly inactivated following 30-40 s exposure to the high-K(+) solution. These results demonstrate, for the first time, that human parathyroid cells express L-type-like Ca(2+) channels that are possibly involved in the [Ca(2+)](o)-induced change in [Ca(2+)](i). This Ca(2+) entry system might provide a compensatory pathway for the negative feedback regulation of parathyroid hormone secretion, especially in hyperplastic conditions in which the Ca(2+)-sensing receptor is poorly expressed.

Morning blood pressure at home predicts erythropoietin-induced hypertension in patients with chronic renal diseases.

BACKGROUND: Correction of anemia by erythropoietin (EPO) is often associated with a rise in blood pressure (BP; EPO-induced hypertension). Most studies regarding EPO-induced hypertension have involved evaluation using office/clinic BP (OBP). However, recent investigations suggest that BP measured at home (HBP) may be of more importance for clinical practice in hypertension. In this context, the present study addressed whether or not HBP measured in the morning could be useful to predict EPO-induced hypertension. METHODS: The study involved patients with mild to moderate renal impairment who had renal anemia requiring EPO treatment. BP control was evaluated based on the relationship between OBP and HBP in the morning. The BP categories used were well-controlled BP, poorly controlled BP, hypertension with a white-coat effect (white-coat hypertension), and masked hypertension. Comparison was made of the BP categories before and after EPO treatment. RESULTS: Before EPO treatment, 38% of patients had well-controlled BP, 30% had poorly controlled BP, 20% had masked hypertension, and 12% had white-coat hypertension, revealing a predominance of morning hypertension (poorly controlled BP plus masked hypertension). Following EPO treatment, the prevalence of morning hypertension in patients with masked hypertension and poorly controlled BP increased significantly, by 5% (HBP in those with masked hypertension increased from 152 +/- 18 mmHg to 162 +/- 25 mmHg, and HBP in those with poorly controlled BP increased from 157 +/- 18 mmHg to 168 +/- 25 mmHg; P < 0.05 by paired t-test). And there was a significant decrease in the prevalence of the well-controlled category, by 8%, with an increased level of morning HBP (from 128 +/- 14 mmHg to 137 +/- 16 mmHg; P < 0.05 by paired t-test). In contrast, OBP remained unchanged in all groups. The development of EPO-induced hypertension was effectively predicted by HBP in the morning (from 62% to 72% before and after EPO treatment; P = 0.0031 by Wilcoxon's analysis), but not by OBP (from 42% to 47% before and after treatment; P = 0.1399). CONCLUSIONS: The present study indicates that, despite receiving concurrent antihypertensive therapy, the majority of patients with renal disease had morning hypertension. Furthermore, HBP in the morning can be more useful than OBP to predict the development of EPO-induced hypertension in patients with renal anemia.

Pseudoaldosteronism due to the concurrent use of two herbal medicines containing glycyrrhizin: interaction of glycyrrhizin with angiotensin-converting enzyme inhibitor.

A 77-year-old man with a history of hypertension and hyperuricemia was admitted to our hospital complaining of limb weakness, persistent constipation, and worsening hypertension. He had been taking a Chinese herbal remedy for allergic rhinitis for the past 10 years, together with an angiotensin-converting enzyme inhibitor (ACE-I; enalapril, 20 mg daily). After the dosage of enalapril had been reduced to 10 mg daily about 1(1/2) years before the current admission, he had developed persistent constipation. Therefore, he had started taking another traditional Chinese herbal remedy, a laxative, for the constipation, about 4 months prior to this hospitalization. Laboratory data on admission demonstrated marked metabolic alkalosis with severe hypokalemia associated with urinary wasting of potassium and chloride. A diagnosis of pseudoaldosteronism was made based upon his past history of exposure to various traditional Chinese medicines containing glycyrrhizin. Discontinuation of the Chinese remedies and supplementation of potassium successfully normalized the electrolyte imbalance and relieved all symptoms within a short time. The present case describes the occurrence of pseudoaldosteronism induced by a patient taking two traditional Chinese herbs, both containing glycyrrhizin, resulting in an overdose of this causative chemical agent. The development of pseudoaldosteronism appeared to be of particular interest with regard to the interaction of the renin-angiotensin-aldosterone (RAA) system with glycyrrhizin, in which an ACE-I retarded the development of pseudoaldosteronism.

[Syndrome of inappropriate ADH secretion (SIADH) induced by pramipexole in a patient with Parkinson's disease].

An 85-year-old woman with Parkinson's disease was admitted to our hospital to conduct a further work-up for progressive gait disturbance. She had been on medications for the disease for more than a decade prior to admission. In order to improve her condition, she was newly administered pramipexole, a dopamine agonist, from day 3 in addition to the preceding anti-Parkinson's therapy. However, on day 10, her consciousness level was rapidly deteriorated into delirium(JCS II-10), which was not accompanied by neurological signs and symptoms. Laboratory tests showed severe hyponatoremia with relatively increased urinary sodium excretion, and severe low serum osmolarity with an increased urinary osmolarity. Brain CT and brain MRI showed no specific abnormalities except for those related to aging. Blood concentration of ADH measured at the onset was substantially higher(39.5 pg/ml) than normal (0.3-3.5 pg/ml under normal osmolarity). Diseases causing hyponatremia, such as liver cirrhosis, congestive heart failure, hypotonic dehydration, and malignancy-associated inappropriate ADH secretion (SIADH), were all excluded. Under the suspicion of SIADH due to pramipexole, the drug was discontinued and as a result, her consciousness level improved rapidly together with a prompt reduction in ADH level (9.2 pg/ml). To the best of our knowledge, the present case is the first that demonstrates pramipexole-induced SIADH. Since pramipexole is classified as a dopaminergic receptor agonist, this case may provide new insight into a link between ADH and the dopaminergic receptor in the central nervous system.

[The role of phosphatonin in phosphate metabolism].

PTH and active vitamin D are well known as classical phosphate regulating hormones. However, presence of some phosphaturic factors is assumed from investigations about TIO, XLH, ADHR. Those diseases cause hypophsophatemia, hyperphosphaturia, low vitamin D and rickets/ostepmalacia. FGF-23, which has been detected from TIO tumors, can induce hypophosphatemia by direct inhibition on phosphate reabsorption and by suppressing 1,25 (OH)(2)D(3) production through the inhibition of 25-hydroxyvitaminD 1alpha-hydroxylase, in the kidney. We have still other phosphatonin candidates such as MEPE, FRP4, etc. The role of these substances are not clear yet. Future investigations are required to clarify their roles in phosphate metabolism.

[Antihypertensive therapy for refractory morning hypertension in patients on peritoneal dialysis].

Due to excessive salt and water retention, hypertension often becomes refractory in patients undergoing peritoneal dialysis (PD). Management of high blood pressure (BP) appears to be of particular importance in such patients because of its substantial impact on the patients' prognosis. However, attempts to control hypertension in PD patients have not been successful in most cases. In this regard, the present study aimed to address the adequacy of current antihypertensive therapy for PD patients. A new antihypertensive strategy expected to improve the outcome was tested on the assumption that treatment with either angiotensin converting enzyme inhibitor (ACE-I) or angiotensin receptor blocker (ARB) in the evening together with alpha1-blocker at bed time and long-acting Ca channel blocker (CCB) in the morning might ameliorate BP control associated with morning hypertension. Enrolled in the present study were 40 patients whose BP was evaluated by both office and home measurement. Due to an emerging concern about morning hypertension, home BP measured early in the morning was used for the analysis. Each patient was categorized into the following four groups in accordance with office and home BP: well-controlled, poorly-controlled, white-coat and masked (opposite to white-coat), hypertension. After the observation period, 28 patients with refractory hypertension were allocated to intensive antihypertensive therapy in which ARB or ACE-I previously prescribed in the morning or daytime was shifted to the night. In addition, alpha1-blocker was given at bed time. Furthermore, long-acting CCB and diuretics were shifted to the morning. The patients were then followed up for 4-6 months. The results were as follows: 1) Of the total number of 40 PD patients, systolic hypertension was noted in 50% of cases by office BP and in 80% by home BP. The former was less frequent than the latter (p=0.0047, n=40). Similarly, diastolic hypertension was noted in 20% by office BP and in 45% by home BP. The former was less frequent than the latter (p=0.0045, n=40 by McNemar's analysis). The distribution of BP control categories was well-controlled in 11%, poorly-controlled in 42%, masked hypertension in 39% and white-coat hypertension in 8% when determined by systolic BP. The distribution was well-controlled in 45%, poorly-controlled in 13%, masked hypertension in 34% and white-coat hypertension in 8% of cases when determined by diastolic BP. 2) In 28 patients subjected to the intensive therapy, the control category of systolic BP was changed from 11 to 37% in well-controlled cases, from 42 to 30% in poorly-controlled cases, from 39 to 26% in masked hypertension cases and from 8 to 7% in white-coat hypertension cases. The shift in categories in both poorly-controlled and masked hypertension cases to the better category (well-controlled), was statistically significant (p=0.001, by Wilcoxon's signed rank test). Similarly, the control category of diastolic BP was changed from 45 to 43% in well-controlled cases, from 13 to 15% in poorly-controlled cases, from 34 to 32% in masked hypertension cases and from 8 to 10% in white-coat hypertension cases. There was a tendency for the prevalence of poorly-controlled and masked hypertension to improve to the well-controlled category in response to intensive therapy (p=0.0625, by Wilcoxon's signed rank test). 3) The plasma concentration of plasminogen activator inhibitor (PAI-1)/tissue plasminogen activator (t-PA) complex (total PAI-1 complex) was significantly decreased after intensive therapy (17.3+/-7.8 ng/ml vs. 13.5+/-4.6 ng/ml, n=28, p<0.01 by paired t-test). In contrast, the plasma concentration of t-PA was unchanged even after intensive therapy (4.8+/-3.9 ng/ml vs. 6.2+/-2.9 ng/ml, n=28, ns). These data suggest that home BP obtained in the morning is a useful measure for evaluating morning hypertension in PD patients, most of whom have refractory hypertension categorized as either poorly-controlled or masked hypertension. Intensive treatment with ACE-I/ARB given in the evening along with alpha1-blocker at bed time combined with a diuretic and/or long-acting CCB in the morning is efficacious in controlling the BP of patients with refractory hypertension in PD patients. The link between the reduction in plasma total PAI-1 levels and the intensive therapy may suggest that this therapeutic strategy could prevent thrombotic events associated with morning hypertension in patients on PD.

Morning blood pressure predicts hypertensive organ damage in patients with renal diseases: effect of intensive antihypertensive therapy in patients with diabetic nephropathy.

Blood pressure (BP) measured at home early in the morning (HBP) has been recognized as a useful predictor for organ damage and has been viewed as an important therapeutic target in patients with hypertension. The present study was aimed to determine whether this notion holds true in patients with progressive renal disease. The study enrolled patients with mild to moderate renal impairment. They were all directed to record self-measured HBP to evaluate the adequacy of BP control. In addition to the conventional antihypertensive therapy, intensive treatment to more efficiently reduce elevated morning HBP was applied, especially in patients with diabetic nephropathy. The results were as follows: 1) The status of BP control assessed using HBP and office/clinic BP (OBP) shows predominance of morning hypertension. The prevalence of patients with well-controlled systolic HBP was 38%, those with poorly-controlled HBP 30%, masked hypertension 20% and white coat hypertension 12%. 2) Early morning systolic HBP in diabetics was significantly higher than that in non-diabetics. However, when evaluated on systolic OBP, both groups were comparable.3)Logistic regression analysis showed that the predictive variables to explain morning hypertension (more than 130 mmHg and increased systolic HBP) were age, amount of daily urinary protein excretion and left ventricular mass index (LVMI).4)Following conventional therapy, intensive antihypertensive therapy consisting of calcium channel blockers (CCB) and/or diuretics given in the morning, and angiotensin receptor blockers (ARB) given in the evening, together with alpha1-blockers given at bedtime, efficaciously reduced elevated HBP in the morning. This result was associated with significant reduction in daily urinary protein excretion and in serum plasminogen-activator inhibitor (PAI-1) concentration. The present study indicates that, regardless of ongoing conventional antihypertensive therapy, the majority of patients with renal disease had morning hypertension, suggesting that these patients are at a higher risk for cardiovascular disease. For the purpose of improving morning hypertension, intensive treatments with combined CCB, ARB and alpha1-blockers could have substantial benefit on the morbidity and prognosis in patients with diabetic nephropathy.