Fujio Deguchi

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)

Measurement of left atrial systolic time intervals in hypertensive patients using Doppler echocardiography: Relation to fourth heart sound and left ventricular wall thickness

The concept of left atrial systolic time intervals and Doppler echocardiography were used in a quantitative assessment of left atrial function in relation to the presence or absence of a fourth heart sound and to left ventricular hypertrophy in 47 patients with hypertension. Left atrial systolic time interval indexes included atrial pre-ejection period (the time between the onset of an electrocardiographic P wave and the onset of left ventricular inflow during atrial systole [A wave]), corrected atrial pre-ejection period (the atrial pre-ejection period divided by the duration of the P wave), and atrial ejection time (the time between the onset and cessation of the A wave). Twenty-one patients with a fourth heart sound on the phonocardiogram had a shorter atrial pre-ejection period (81 +/- 10 versus 89 +/- 14 ms p less than 0.05) and a corrected atrial pre-ejection period (66 +/- 17 versus 83 +/- 18 ms, p less than 0.01), as well as a longer atrial ejection time (147 +/- 15 versus 126 +/- 13 ms, p less than 0.001) than did 26 patients without a fourth heart sound. The ratio of atrial pre-ejection period to atrial ejection time and that of corrected atrial pre-ejection period to atrial ejection time was smaller in patients with than in patients without a fourth heart sound (0.56 +/- 0.08 versus 0.71 +/- 0.11, p less than 0.001; 0.46 +/- 0.16 ms-1 versus 0.67 +/- 0.17 ms-1, p less than 0.001, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Changes in Dietary Sodium Intake and Saline Infusion on Plasma Atrial Natriuretic Peptide in Hypertensive Patients

Plasma concentrations of immunoreactive (IR)-atrial natriuretic polypeptide (hANP) were measured by radioimmunoassay in 9 essential hypertensive patients after alteration of salt intake and acute saline infusion. Daily salt intake was altered every one week in the order of 15g/day, 3g/day, and 7g/day. On the last day of the first week, 1500 ml of 0.9% saline was infused intravenously over one hour. Plasma concentrations of IR-hANP tended to decrease, although not significant, by salt restriction. Further, there were significant positive correlations between changes in plasma concentrations of IR-hANP and those of several variables such as body weight, systolic blood pressure, and creatinine clearance. Plasma concentrations of IR-hANP rose significantly (p less than 0.05) from 50.7 +/- 20.1 (Mean +/- SEM) pg/ml to 119.0 +/- 48.8 after acute saline infusion. Although there was significant correlation between mean blood pressure and the increase in sodium excretion by saline infusion, this increase was unrelated to the rise in plasma concentrations of IR-hANP. These results suggest that the release of ANP is stimulated mainly by expansion of extracellular fluid volume in hypertensive patients. However, natriuretic and hypotensive effects attributable to the changes of ANP release could not be elucidated.