Proteomic profile of circulating immune complexes in chronic Chagas disease.

Immune complexes (ICs) are the direct and real-time products of humoral immune responses. The identification of constituent foreign or autoantigens within ICs might bring new insights into the pathology of infectious diseases. We applied immune complexome analysis of plasma to the study of Chagas disease caused by Trypanosoma cruzi. Twenty seropositive plasma samples including cardiac and/or megacolon determinate patients (n = 11) and indeterminate (n = 9) were analysed along with 10 seronegative individuals to characterize the antigens bound to circulating ICs. We identified 39 T. cruzi antigens and 114 human autoantigens specific to patients with Chagas. Among those antigens, two T. cruzi antigens (surface protease GP63, glucose-6-isomerase) and six human autoantigens (CD180 antigen, ceruloplasmin, fibrinogen beta chain, fibrinogen beta chain isoform 2 preprotein, isoform gamma-A of fibrinogen γ-chain, serum paraoxonase) were detected in more than 50% of the patients tested. Human isoform short of complement factor H-related protein 2 and trans-sialidase of T. cruzi were more frequently found in the indeterminate (5/9 for both) compared with in the determinate Chagas (0/11, P = 0·046 for human, 1/11, P = 0·0498 for T. cruzi). The immune complexome could illustrate the difference of immune status between clinical forms of chronic Chagas disease.

Calcium supplementation in patients with essential hypertension: assessment by office, home and ambulatory blood pressure.

OBJECTIVE: To study the effects of a high calcium intake in hypertensive patients by blood pressure monitoring. DESIGN: In a randomized crossover study, patients were assigned to an 8-week calcium supplementation period and an 8-week control period. The subjects were given 25 mmol/day (1 g/day) of calcium as calcium carbonate during the intervention period. SETTING: A hypertension clinic in a tertiary teaching hospital. PATIENTS: Sixty untreated or treated hypertensive patients (35 men and 25 women, mean age 58 years) with office systolic/diastolic blood pressure > or = 140/90 mmHg. MAIN OUTCOME MEASURES: Office blood pressure, home blood pressure (last 7 days), and ambulatory 24 h blood pressure (every 30 min using TM-2421). RESULTS: The serum calcium concentration and urinary calcium excretion increased significantly with calcium supplementation. Office, home and 24 h blood pressure were lower in the calcium period than in the control period, although the differences were small (mean +/- SEM office blood pressure: 1.2+/-1.2/1.1+/-0.7 mmHg; home blood pressure: 1.9+/-0.7/1.3+/-0.6 mmHg; 24 h blood pressure: 1.2+/-0.8/0.9+/-0.5 mmHg,), and significant only for home systolic and diastolic blood pressures. The difference in home systolic blood pressure was inversely correlated with the level of home blood pressure in the control period and with the difference in urinary calcium. The difference in 24 h systolic blood pressure was positively correlated with the control level of urinary calcium. Age, sex, antihypertensive medication, drinking habit, sodium intake or order of treatment did not significantly influence the effects of calcium supplementation. CONCLUSIONS: An increase in calcium intake tends to lower office, home and ambulatory blood pressure in hypertensive patients. However, the antihypertensive effect is too small to support the general application of a high calcium intake in the treatment of hypertension.

Effect of cilazapril and salt on Ca2+ extrusion in arterial smooth muscle of Dahl rats.

We examined effects of salt and cilazapril on the Ca pump and Na/Ca exchange system in arterial smooth muscle of Dahl salt-sensitive (DS) rats. Twenty-four DS rats were assigned to four groups. H and H+ rats were fed a high salt diet; L- and L+ rats were fed a low salt diet. H+ and L+ were administered cilazapril. Aortic rings were superfused with physiologic saline and isometric tension was measured. Relaxation of low Na+-induced contraction was promoted by the removal of external Ca. Cilazapril significantly decreased blood pressure in both the high and low salt diet groups. The inhibition of renin-angiotensin system by cilazapril showed that Ca extrusion by ATP-driven Ca pump was decreased by salt loading, and that Ca extrusion by Na/Ca exchange was increased by salt loading. There was a negative correlation between Ca extrusion by Ca pump and blood pressure, and a positive correlation between Ca extrusion by Na/Ca exchange and blood pressure. These results suggest that the decrease of Ca2+ extrusion by ATP-driven Ca pump resulting from a high salt diet might lead to an elevation in the concentration of cellular Ca2+ and contribute to the mechanism of hypertension in DS rats, and that Ca2+ extrusion by the Na/Ca exchange might be increased in compensation for an increase in cellular Ca2+ concentration on the high salt diet.

Effect of the Hanshin-Awaji earthquake on home blood pressure in patients with essential hypertension.

At 5:46 AM on January 17, 1995, the Hanshin-Awaji district of Japan was struck by a major earthquake. We investigated changes in home blood pressure (BP) of 36 hypertensive patients before and after the earthquake. In the 16 patients who lived within 50 km from the epicenter, the home Bp on the day of the earthquake was significantly higher than that just before the earthquake (+11/+6 mm Hg; P < .01 for systolic BP and P < .05 for diastolic BP). It remained higher throughout the first week after the earthquake, then gradually returned to the baseline level within 4 weeks. The home BP did not change significantly in the 20 patients who lived farther than 50 km from the epicenter. The earthquake-induced stress increased the BP in these hypertensive patients; however, its pressor effect was not persistent.

Different effects of alcohol and salt on 24-hour blood pressure and heart rate in hypertensive patients.

To compare the influences of alcohol and salt intake on 24-h blood pressure (BP), we studied short-term effects of repeated alcohol ingestion and dietary salt intake in hypertensive patients. Thirty-two Japanese men with mild to moderate essential hypertension (54 +/- 1 years old, mean +/- SE) were examined. Sixteen patients were given alcohol (1 ml/kg) with dinner for 7 d after a 7-d control period with an isocaloric beverage. Another group consisting of 16 age- and weight-matched patients consumed a low-sodium diet (25 mmol/d) for 7 d, followed by a high-sodium diet (250 mmol/d) for 7 d. Twenty-four-hour BP was measured at the end of each period. Average 24-h BP in the alcohol period (137 +/- 4/83 +/- 2 mmHg) was similar to that in the control period (138 +/- 4/84 +/- 2 mmHg). However, BP in the alcohol period was significantly lower in the evening, but significantly higher in the morning than that in the control period. Heart rate increased for several hours after alcohol ingestion, resulting in a significant increase in 24-h heart rate (67 +/- 2 vs. 64 +/- 2 beats/min). Average 24-h BP was higher in the high salt period (144 +/- 4/89 +/- 4 mmHg) than in the low salt period (135 +/- 3/85 +/- 3 mmHg, p < 0.05). The pressor effect of high salt intake was sustained throughout the day and was associated with a decrease in 24-h heart rate (60 +/- 2 vs. 66 +/- 2 beats/min). In conclusion, short-term repeated intake of alcohol may have little effect on average 24-h BP while it causes an evening fall and a morning rise in BP, and high salt intake raises BP throughout the day. Alcohol consumption increases and salt loading decreases 24-h heart rate.

Seasonal variations in office, home and 24 h ambulatory blood pressure in patients with essential hypertension.

OBJECTIVE: To study the influence of seasons on blood pressure in ordinary circumstances. DESIGN AND METHODS: We examined seasonal variations of home and 24 h ambulatory and office blood pressures in outpatients with essential hypertension. Office, home and ambulatory blood pressures of 50 outpatients with essential hypertension were recorded in 1993. The subjects were 26 women and 24 men, aged 59.3 +/- 1.1 years (mean +/- SEM). Office blood pressure was measured monthly by physicians. Home blood pressure was measured every day by the patients in the morning and evening. Ambulatory blood pressure was recorded every 30 min in summer and in winter. The order of ambulatory blood pressure monitoring was randomized. The daytime and night-time blood pressures were calculated according to the true waking and sleeping times of the individual patients. RESULTS: Both office and home blood pressures showed significant seasonal variations. The winter-summer differences in office and home blood pressures were 4.7 +/- 1.3/ 3.3 +/- 0.9 and 5.9 +/- 1.1/2.7 +/- 0.6 mmHg, respectively. They were not influenced by the presence of antihypertensive agents. The winter-summer difference was also significant for daytime ambulatory blood pressure (3.5 +/- 1.4/ 2.5 +/- 0.8 mmHg), but not for night-time ambulatory blood pressure (-2.9 +/- 1.7/-1.2 +/- 1.0 mmHg) or average 24 h blood pressure (1.5 +/- 1.3/1.2 +/- 0.7 mmHg). There were no significant differences in the waking and sleeping times between the two seasons. CONCLUSIONS: Office, home and daytime ambulatory blood pressure levels were higher in winter than they were in summer in patients with essential hypertension. However, the seasonal variations in average 24 h blood pressure may be small because of the lack of changes in night-time blood pressure.

Pressor and depressor hormones during alcohol-induced blood pressure reduction in hypertensive patients.

Alcohol acutely causes vasodilation and hypotension in Orientals. To study the mechanisms responsible for the alcohol-induced blood pressure (BP) reduction, we examined levels of various vasoactive hormones after a single intake of alcohol in twelve Japanese men with mild hypertension. On the alcohol intake day, they consumed 1 ml/kg of alcohol with an evening meal, while on the control day they took an isocaloric control drink. BP and vasoactive hormone levels were determined before and 2 h after intake of the alcohol or the control drink. BP after alcohol ingestion was significantly lower than that before drinking or on the control day. This alcohol-induced hypotension was associated with significant increases in heart rate, plasma catecholamines and plasma renin activity (PRA). The changes in heart rate and plasma noradrenaline were inversely related to the changes in BP. Plasma levels of vasopressin and insulin were lower in the alcohol period than in the control period, but these changes were not correlated with the changes in BP. Levels of aldosterone, cortisol, atrial natriuretic peptide, prostaglandin (PG) E2, 6-keto-PGF1 alpha, beta-endorphin, and cyclic GMP were not significantly different between the alcohol and the control periods. These results suggest that changes in pressor hormones may not contribute to the acute hypotensive effect of alcohol, and that the sympathetic nervous system is activated by the BP reduction. The levels of the depressor hormones measured also appear to play no role in alcohol-induced hypotension.

Effects of dietary salt and angiotensin-converting enzyme inhibitor on ATP-driven Ca pump and Na/Ca exchange in aortic rings of Dahl rats.

We examined effects of dietary salt and cilazapril on ATP-driven Ca pump and Na/Ca exchange system in arterial smooth muscle of Dahl salt-sensitive (DS) rats. Twenty-four DS rats were assigned to 4 groups. H- and H+ rats were fed a high-salt diet. L- and L+ rats were fed a low-salt diet. H+ and L+ were administered cilazapril. Aortic rings were superfused with physiological saline, and isometric tension was measured. Relaxation rates of low-Na(+)-induced contractions were promoted by the removal of external Ca. Cilazapril significantly decreased blood pressure in both the high- and low-salt diet groups. Salt loading reduced relaxation rates in 1.2 mmol/l Na+, and enhanced the increase in relaxation rates from 1.2 mmol/l to normal Na+. A negative correlation was observed between Ca extrusion by the Ca pump and blood pressure, and a positive correlation was observed between Ca extrusion by Na/Ca exchange and blood pressure. The results suggest that the decrease of Ca2+ extrusion by the ATP-driven Ca pump resulting from a high-salt diet might lead to an elevation in the concentration of cellular Ca2+.

A case of splenic artery aneurysm with Cushing's syndrome.

We report here a case of splenic artery aneurysm with Cushing's syndrome. Pregnancy and the increased secretion of cortisol from an adrenal adenoma in Cushing's syndrome may affect the intimal and medial degeneration. Factors other than glucocorticoids may influence the pathological changes.

Changes in plasma endothelin-1 concentration during blood volume depletion and expansion: role of the cardiopulmonary baroreflex.

To study the relationship between blood volume and the plasma level of endothelin-1 (ET-1), we examined the effects of blood volume depletion and expansion on the plasma ET-1 level in the rat. Anesthetized Wistar rats were subjected to hemorrhage (7 ml/kg), blood transfusion (7 ml/kg), or sham treatment. The same blood volume depletion and expansion were performed in other groups of rats, after bilateral cervical vagotomy or administration of intravenous atropine, to examine the role of the cardiopulmonary baroreflex. Hemorrhage produced mild decreases in the central venous pressure and arterial blood pressure, and an increase in the heart rate. Blood transfusion caused the opposite responses. The plasma ET-1 level was significantly higher in the volume-depleted rats (4.7 +/- 0.4 pg/ml, mean +/- SE, p < 0.05 vs. control), and was lower in the volume-expanded rats (2.6 +/- 0.2 pg/ml, p < 0.05) than in the control group (3.5 +/- 0.3 pg/ml). In the vagotomized rats, the blood volume depletion decreased and the volume expansion increased the central venous pressure and the arterial pressure, but they did not change the heart rate or the plasma ET-1 level. Vagal efferent inhibition with atropine did not affect the volume-induced changes in the plasma ET-1 level. These results indicate that the plasma level of ET-1 increases with blood volume depletion, and decreases with volume expansion. The cardiopulmonary baroreflex may play an important role in the regulation of plasma ET-1 levels when the blood volume is altered.

Rapid increase in plasma endothelin concentrations during percutaneous balloon dilatation of the mitral valve in patients with mitral stenosis.

OBJECTIVE: To investigate the relation between plasma concentrations of immunoreactive endothelin and haemodynamic variables before and after percutaneous transvenous balloon dilatation of the mitral valve. DESIGN: Prospective study. SETTING: National cardiovascular centre. PATIENTS: 25 patients with mitral stenosis and 26 healthy volunteers. MAIN OUTCOME MEASURES: Plasma concentrations of immunoreactive endothelin were measured in the pulmonary artery, left atrium, ascending aorta, and femoral vein before and after balloon dilatation of the mitral valve. RESULTS: Peripheral venous concentrations (mean (SD)) of endothelin were higher in the patients with mitral stenosis than in the healthy volunteers (1.76 (0.51) v 1.37 (0.45) pg/ml, p < 0.05) and they correlated with the mean left atrial pressure (r = 0.74, p < 0.01). Balloon dilatation of the mitral valve reduced the mean left atrial pressure without changing the mean right atrial pressure, systemic arterial pressure, heart rate, or cardiac index. Concentrations of plasma endothelin in the femoral vein increased from 1.76 (0.51) to 3.39 (2.46) (p < 0.01), 4.82 (2.34) (p < 0.001), and 2.43 (0.52) pg/ml (p < 0.05) at 15 and 30 minutes and 24 hours after the procedure. The concentration of endothelin in the pulmonary artery also increased from 1.85 (0.85) to 4.32 (1.58) pg/ml (p < 0.01) 30 minutes after the dilatation, whereas there were no appreciable changes in endothelin concentration in the left atrium or ascending aorta. CONCLUSIONS: Plasma endothelin concentrations were higher in patients with mitral stenosis than in healthy volunteers and the increase was proportional to left atrial pressure. After balloon dilatation of the mitral valve there was an abrupt rise in endothelin in the femoral vein and pulmonary artery but no change in left atrial or aortic blood samples. These findings suggest that endothelin may be another vasoactive substance involved in congestive heart failure.

Acute effects of alcohol ingestion on blood pressure and erythrocyte sodium concentration.

OBJECTIVE: To examine the acute effects of alcohol on blood pressure and erythrocyte cation concentrations in patients with essential hypertension. DESIGN: An alcoholic drink or an isocaloric control drink was given during supper in random order on different days, and blood pressure and erythrocyte cation concentrations were measured before and 2 h after the meal. METHODS: The subjects were 21 men with essential hypertension who habitually drank alcohol. Blood pressure was measured with a semi-automated sphygmomanometer, and erythrocyte cation concentrations were measured by flame photometry after haemolysis with distilled water. RESULTS: Blood pressure decreased after both drinks, but the decrease was significantly larger after the alcoholic drink than after the control drink. There was a significant difference between the changes in erythrocyte sodium caused by the alcoholic and the control drink. Furthermore, there were significant positive correlations between the fall in blood pressures and the decrease in erythrocyte sodium concentration. CONCLUSION: The predominant acute effect of alcohol ingestion in patients with hypertension is blood pressure reduction, and it may be associated with a decrease in intracellular sodium.

Effects of dietary salt on sodium-calcium exchange and ATP-driven calcium pump in arterial smooth muscle of Dahl rats.

AIM: To compare the effects of dietary salt on sodium-calcium exchange and the ATP-driven calcium pump in arterial smooth muscle between Dahl salt-sensitive (DS) and salt-resistant (DR) rats. METHODS: Aortic rings freshly excised from 16 DS rats and 16 DR rats on a low- (0.3%) or high- (8%) NaCl diet for 4 weeks were superfused with physiological saline and isometric tension was measured. In the presence of 10 mumol/l phentolamine, 10 mumol/l verapamil and 5 mmol/l caffeine, relaxation of a low-Na+ contraction was promoted by external calcium removal. RESULTS: On the high-salt diet, the rate of relaxation at 1.2 mmol/l extracellular sodium (calcium extrusion by calcium ATPase) was significantly lower in aortic rings from DS rats than from DR rats. The increase in the rates of relaxation from 1.2 mmol/l to normal (139.2 mmol/l) extracellular sodium (calcium extrusion by sodium-calcium exchange) was significantly greater with the high-salt diet than with the low-salt diet in rings from DR rats, but it was not different between the high- and low-salt diets in DS rats. The rate of increase in tonic tension by reducing extracellular Na+ from normal to 1.2 mmol/l in the presence of verapamil, caffeine and phentolamine (calcium entry by sodium-calcium exchange) was significantly lower in rings from DS rats than in those from DR rats on the high-salt diet. CONCLUSIONS: These observations suggest that the effects of dietary salt on the sodium-calcium exchange system in arterial smooth muscle differ between DS and DR rats and that calcium extrusion by the calcium pump is decreased in DS rats compared with DR rats. The lack of an increase in sodium-calcium exchange in salt-fed DS rats might lead to an elevation in cellular calcium and contribute to the mechanism of hypertension.

Acute depressor effect of alcohol in patients with essential hypertension.

To investigate the time course of the effects of alcohol on blood pressure, we studied the response of ambulatory blood pressure, neurohumoral variables, and hemodynamics to a single moderate dose of alcohol in hypertensive patients. Sixteen Japanese men (22-70 years old) with essential hypertension who were habitual drinkers were examined under standardized conditions. On the alcohol intake day, they ingested 1 ml/kg ethanol (vodka) at dinner, and on the control day they consumed a nonalcoholic beverage. The order of the two periods was randomized. Mean ambulatory blood pressure was lower in the alcohol intake period than in the control period (125 +/- 3/74 +/- 2 versus 132 +/- 4/78 +/- 2 mm Hg, p less than 0.05), and the significant depressor effect of alcohol lasted for up to 8 hours after drinking. Blood pressure on the next day did not differ with or without alcohol intake. The acute hypotensive effect of alcohol was associated with an increase in heart rate and cardiac output and with a decrease in systemic vascular resistance as determined by echocardiography. Plasma catecholamine levels and renin activity rose significantly at 2 hours after dinner, whereas vasopressin and potassium levels fell on the alcohol day. Blood glucose and serum insulin levels were comparable between the two periods. Three patients with marked alcohol-induced flush had greater hypotensive and tachycardiac responses than those who did not show an alcohol-induced flush. The change in mean blood pressure induced by alcohol was negatively correlated with age, the baseline blood pressure, and the change in plasma norepinephrine. These results indicate that the major effect of acute alcohol intake is to lower blood pressure through systemic vasodilatation in hypertensive subjects. Ambulatory blood pressure monitoring may be useful for assessing blood pressure in habitual drinkers.

Sodium and noradrenaline in cerebrospinal fluid and blood in salt-sensitive and non-salt-sensitive essential hypertension.

1. The effects of dietary sodium on blood pressure and levels of sodium, other electrolytes and noradrenaline (NA) in the cerebrospinal fluid (CSF) and blood of 15 patients with essential hypertension were studied. The CSF and blood sampling was carried out after 7 days of a high salt intake (16-18 g/day) and after 7 days of a low salt intake (1-3 g/day). 2. Blood pressure and sodium concentrations in CSF and serum were significantly higher in the high salt period than the low salt period (CSF Na+ concentration: 147.7 +/- 0.4 mmol/L vs 145.3 +/- 0.5 mmol/L; P less than 0.001). Levels of CSF pressure and potassium or calcium concentrations were not different between the two periods. Plasma NA and plasma renin activity (PRA) were lower and CSF NA levels tended to be lower in the high salt period. 3. The levels and the changes in sodium and NA in CSF were not significantly different between the salt-sensitive (n = 8) and the non-salt-sensitive (n = 7) subjects, but the changes in plasma NA and PRA were smaller in the salt-sensitive subjects. 4. These results indicate that the sympathetic nervous system is less suppressed in salt-sensitive subjects during high salt intake. This may be due to altered neural responsiveness to sodium loading rather than being greater increases in sodium concentration in the central nervous system.

Effect of manidipine, a new calcium antagonist, on intrarenal hemodynamics in essential hypertension.

The effect of manidipine, a new Ca2+ antagonist, on intrarenal hemodynamics was assessed in essential hypertension and compared with nicardipine, a previously studied Ca2+ antagonist. Identical 2-week studies were repeated before and during the administration of manidipine (10 mg once daily, 2 weeks) in 3 patients with essential hypertension who were given regular- and sodium-restricted diets for 1 week each. The renal function curve (pressure-natriuresis relationship) was drawn by plotting the urinary sodium excretion rate on the y-axis as a function of the systemic mean arterial pressure (MAP) on the x-axis. Assuming that the difference between MAP and the extrapolated x-intercept of the renal function curve represents the effective filtration pressure across the glomerular capillary walls, the intrarenal hemodynamics were calculated (e.g., afferent arteriolar resistance (RA), efferent arteriolar resistance (RE), and glomerular pressure (PG)). During the regular sodium diet, MAP was lowered from 100 +/- 7 to 93 +/- 5 mmHg (p < 0.04) and the effective filtration pressure was lowered from 20 +/- 2 to 10 +/- 3 mmHg (p < 0.05); the renal plasma flow rate (pre: 560 +/- 74 vs. post: 627 +/- 108 mL/min) and glomerular filtration rate (82 +/- 10 vs. 78 +/- 5 mL/min) were not altered. RA remained unchanged (3,800 +/- 700 vs. 3,400 +/- 300 dyn.sec.cm-5; % reduction: 4 +/- 16%) whereas RE was reduced from 4,300 +/- 700 to 3,300 +/- 800 dyn.sec.cm-5 (19 +/- 15%). Thus, PG was lowered from 58 +/- 2 to 50 +/- 2 mmHg (13 +/- 3%), which parallels with the reduction in MAP.(ABSTRACT TRUNCATED AT 250 WORDS)

Intrarenal hemodynamics in patients with essential hypertension.

Intrarenal hemodynamics were estimated clinically in essential hypertension. Two-week studies were performed in 30 patients with essential hypertension who were given a regular sodium diet in the first week and a sodium-restricted diet in the second week. Intrarenal hemodynamic parameters such as afferent arteriolar (preglomerular) resistance, efferent arteriolar resistance, and glomerular hydrostatic pressure were calculated from renal clearances and plasma total protein concentration measured on the last day of the regular sodium diet. Calculations were based on Gomez's equations with the assumption that the gross filtration coefficient of glomerular capillaries was normal. The increase in afferent arteriolar resistance (8,100 +/- 500 dyne.sec.cm-5) was significantly correlated with an elevation in mean arterial pressure (120 +/- 2 mm Hg), whereas glomerular pressure (56 +/- 1 mm Hg) and efferent arteriolar resistance (2,500 +/- 100 dyne.sec.cm-5) remained normal. The renal function curve (pressure-natriuresis relation) was drawn by plotting urinary sodium excretion on the y axis as a function of mean arterial pressure on the x axis, both of which were measured on the last 3 days of each week. The extrapolated x intercept (107 +/- 2 mm Hg) of the renal function curve was strongly correlated in a 1:1 fashion with the sum of the arterial pressure drop from the aorta to the renal glomeruli plus the opposing pressures against glomerular filtration at glomeruli (r = 0.7, p less than 0.001) on the regular sodium diet, suggesting that the difference between mean arterial pressure on the regular sodium diet and the extrapolated x intercept represented the effective filtration pressure across the glomerular capillaries on the regular sodium diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of a calcium-entry blocker, nicardipine, on intrarenal hemodynamics in essential hypertension.

The effects of a calcium-entry blocker, nicardipine, on intrarenal hemodynamics were studied in essential hypertension. A 4-week study was performed in eight patients with essential hypertension who were given a regular sodium diet in the first and third weeks, and a sodium-restricted diet in the second and fourth weeks. Nicardipine, 60 mg/d, was administered in the third and fourth weeks. The urinary sodium excretion rate (UNaV) was plotted on the y-axis against the mean arterial pressure (MAP) on the x-axis before and after the administration of nicardipine. Assuming the difference between MAP and the x-intercept of this renal function curve represents the effective filtration pressure across the glomerular capillaries, the intrarenal hemodynamics such as afferent arteriolar resistance (RA) and efferent arteriolar resistances (RE), glomerular pressure (PG), and gross filtration coefficient (KFG) were calculated. Although the MAP on regular salt diet was lowered from 125 +/- 3 to 109 +/- 2 mm Hg by nicardipine, neither the renal blood flow rate (RBF) (670 +/- 40 mL/min) nor the glomerular filtration rate (GFR) (79 +/- 2 mL/min) was altered. The RA was estimated to be reduced from 9,300 +/- 900 to 7,400 +/- 700 dyne.s.cm-5 (P less than 0.01), while no changes were noted in RE (4,900 +/- 400 dyne.s.cm-5), PG (50 +/- 1 mm Hg), or KFG (0.180 +/- 0.041 [mL/s]/mm Hg). Essential hypertension has been characterized by a prominent increase in RA, resulting in maintenance of normal PG. This Ca-entry blocker worked to normalize intrarenal hemodynamics in essential hypertension by dilating afferent arterioles alone.(ABSTRACT TRUNCATED AT 250 WORDS)