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Biomedical subjects

F V Costa

Publications and source records attributed to F V Costa.

At least 55 records · Page 3Linked to original sources
PubMed1986

Influence of captopril on intracellular ions--a possible mode of action.

The effects on intra- and extracellular Na+ and K+ (Nai, Ki; Nae, Ke) of 2 months treatment with captopril or hydrochlorothiazide given alone or in combination were assessed in 47 hypertensive patients. Before therapy, diastolic blood pressure was directly related to Nai and to Nai/Ki and inversely to Ki. The correlation coefficient was even higher when Ki/Ke was considered instead of Ki alone. Treatment with captopril induced a decrease in Nai, no change in Ke and an increase in Ki and Ki/Ke. Hydrochlorothiazide induced a decrease in Nai, in Ke and in Ki but an increase in Ki/Ke. The Nai decrease was maximal in patients receiving the combination of captopril and hydrochlorothiazide. In these subjects Ke was not reduced and Ki was still increased. The percent reduction in diastolic blood pressure induced by captopril was significantly related to the percent increase in Ki/Ke whereas the reduction induced by hydrochlorothiazide was best related to the decrease in Nai/Nae. These data suggest that blood pressure is related to the Ki/Ke ratio and that any increase in this ratio could produce a fall in blood pressure. This phenomenon can be explained by the Ki/Ke ratio being an important factor in determining membrane potential and thus arterial smooth muscle tone.

Adult↗
PubMed1985

Differing dosages of captopril and hydrochlorothiazide in the treatment of hypertension: long-term effects metabolic values and intracellular electrolytes.

The effects of long-term treatment with differing dosages of captopril and hydrochlorothiazide in combination were evaluated in 22 hypertensive patients. There was no significant difference in antihypertensive efficacy between captopril 25 mg twice a day in combination with hydrochlorothiazide 25 mg once or twice daily and captopril 50 mg twice a day in the same combination. About 75% of patients achieved normotension. Once daily therapy with captopril 50 mg and hydrochlorothiazide 25 mg was effective in only 25% of patients. Long-term treatment (11 months) with captopril and hydrochlorothiazide did not cause any of the metabolic effects usually observed during diuretic administration. Intracellular (lymphocytic) Na+ was significantly reduced and intracellular K+ significantly increased by captopril and hydrochlorothiazide, and this led to the normalization of the intracellular Na+:K+ ratio, which is abnormally high in essential hypertension. Our data suggest that the association of low doses of captopril and hydrochlorothiazide is highly effective, well tolerated, prevents the metabolic side effects of diuretics, and has favorable effects on intracellular ionic composition.

Adult↗
PubMed1985

Comparison of two automatic devices and the standard mercury sphygmomanometer in hypertensive patients.

The standard mercury sphygmomanometer (SMS) and two automatic blood pressure recording devices, Dinamap 845 (D) and Sentron (S), were compared by means of a randomized 3-period cross-over experiment. Both devices recorded diastolic BP lower than SMS, on average and for most individual patients. Systolic BP was similar for SMS and S, and slightly lower for D, with variations for individual patients. A second study failed to detect effects of the physician's presence when BP was measured, whereas the difference between D and SMS was substantially confirmed.

Blood Pressure↗
PubMed1985

Plasma Na+-K+ ATPase inhibitory activity in normal and hypertensive subjects: relationship to intracellular electrolytes and blood pressure.

The ability of plasma extracts to inhibit Na+-K+ ATPase in vitro (P.I.A.) was tested in 20 normotensives, 10 without (F-) and 10 with (F+) familial hypertension, in 20 borderlines (BL) and in 21 essential hypertensives (EH). In these subjects we also measured intralymphocytic sodium (ILSC) and potassium (ILKC) content, P.R.A. urinary aldosterone and Na+(Na+u), and blood pressure. P.I.A. of EH, BL and F+ subjects was significantly higher than that of F-. 60% of EH and BL and 40% of F+ had P.I.A. values greater than the highest found in F-. P.I.A. was significantly related to mean blood pressure (r = 0.63), to ILSC (r = 0.56), to ILKC (r = -0.56), to ILSC/ILKC ratio (r = 0.71) and to Na+u (r = 0.39) but not to P.R.A. or aldosterone. These data demonstrate that plasma extracts from young subjects prone to hypertension may inhibit sodium pump and that this inhibitor may affect blood pressure by altering the Na+/K+ intracellular ratio.

Adult↗
PubMed1985

Modifications of intra- and extracellular sodium and potassium. A possible mechanism for the antihypertensive action of captopril and hydrochlorothiazide.

Forty-four essential hypertensive patients were studied during placebo and after 2 months of the following treatments: hydrochlorothiazide 25 mg once daily (group 1); captopril 50 mg twice daily (group 2); hydrochlorothiazide + captopril (group 3). Blood pressure, serum sodium and potassium (Nae, Ke) and intralymphocytic sodium and potassium (Nai, Ki) were measured before and after treatment. During placebo, diastolic blood pressure was directly related to Nai (r = -0.84) and inversely related to Ki (r = -0.81). The correlation was even greater when the Ki:Ke ratio was considered instead of Ki alone (r = -0.91). Hydrochlorothiazide reduced Nai, Ke and Ki. Captopril induced a decrease in Nai, an increase in Ki and no change in Nae or Ke. The association of the two drugs caused a reduction in Nae and Nai and an increase in Ki. All three treatments caused an increase in Ki:Ke ratio which was proportional to the decrease in the blood pressure. While the antihypertensive effect of hydrochlorothiazide seems to be more related to Nai:Nae reduction, the effect of captopril seems to be more related to the increase in Ki:Ke ratio. The results of our study suggest that hyperpolarization of arterial smooth muscle cells, induced by a Ki:Ke ratio increase, along with a reduction in Nai:Nae, might play a role in the antihypertensive effect of captopril and hydrochlorothiazide.

Adult↗
PubMed1985

Antihypertensive efficacy of two low dosages of hydrochlorothiazide in patients treated with captopril.

Twelve patients with essential hypertension (diastolic blood pressure, greater than 90 mmHg) after four weeks of treatment with captopril (50 mg BID) were randomly divided into two groups and treated with 12.5 mg and 25 mg of hydrochlorothiazide OD, in addition to captopril, in a crossover experimental design. Each dosage of hydrochlorothiazide was given for four weeks, with a two-week placebo washout period intervening. Both dosages of hydrochlorothiazide caused significant reductions in blood pressure. Eighty percent of patients achieved a diastolic blood pressure less than 90 mmHg during combination therapy, independent of the dose of diuretic. None of the patients reported significant side effects, and no changes were observed in routine biochemical analysis during treatment. In patients not completely controlled by captopril alone, a once-daily dosage of 12.5 mg of hydrochlorothiazide proved as effective as a 25-mg once-daily dosage. The smaller dosage could result in fewer unwanted metabolic effects induced by diuretic administration.

Adult↗
PubMed1984

Cardiovascular response to mental stress: dynamic and isometric exercise in hypertensive patients treated with prizidilol hydrochloride (SK&F 92657).

The cardiovascular effects of a new antihypertensive agent, prizidilol hydrochloride (SK&F 92657), have been evaluated in a group of 13 patients with mild to moderate essential hypertension, both at rest and during mental stress and isometric or dynamic exercise. After 6 weeks of therapy (200-300 mg of prizidilol b.i.d.) both systolic and diastolic blood pressure values at rest were significantly lower than those recorded before treatment and during placebo (with an average decrease of about 22/11 mm Hg in the supine position). Heart rate at rest was slightly reduced. Cardiovascular responses to dynamic exercise and mental stress were not prevented by prizidilol, but blood pressure and heart rate levels around which variation occurred were lowered to a significant extent. During isometric exercise prizidilol did not protect against a rise in diastolic blood pressure. Blood pressure and heart rate reduction both at rest and during stimulation were not related to plasma drug concentrations. Side-effects were very rare. It is concluded that prizidilol significantly reduces blood pressure both at rest and during mental stress and physical activity with only sight effects on heart rate, and with a very simple therapeutic scheme.

Adrenergic beta-Antagonists↗
PubMed1984

Captopril and oxprenolol in a fixed combination with thiazide diuretics: comparison of their antihypertensive efficacy and metabolic effects.

After receiving placebo for two weeks, 20 patients with essential hypertension were randomly divided into two groups. Those in group 1 received a combination of 25 mg of captopril (CPT) and 25 mg of hydrochlorothiazide (HCT) BID. Those in group 2 received a combination of 80 mg of oxprenolol (OXP) and 10 mg of chlorthalidone (CHLT) BID. Patients whose recumbent diastolic blood pressure was less than 95 mmHg after four weeks of treatment continued with the same regimen for six more weeks, while the dosages were doubled for nonresponders. All the patients in group 1 had satisfactory blood pressure readings after the first four weeks of therapy; six patients in group 2 required double dosages to control their blood pressure. Both drug combinations reduced patients' recumbent systolic blood pressure, but CPT + HCT reduced their diastolic and standing systolic blood pressure more effectively. Doubling the dosages of OXP + CHLT was only slightly more effective in controlling patients' blood pressure. In addition, patients who received CPT + HCT showed a significant decrease in serum sodium level, whereas patients who received the double dosages of OXP + CHLT showed a significant increase in serum cholesterol and creatinine levels. The data suggest that low dosages of CPT + HCT control blood pressure more effectively than high dosages of OXP + CHLT and, in addition, do not have any negative metabolic effects.

Adult↗
PubMed1983

Relationship between intralymphocytic sodium content and pressor response to mental arithmetic and static exercise in essential hypertension.

The relationship between intralymphocytic sodium content (ILSC) and blood pressure (BP) was assessed in a group of 18 untreated patients with essential hypertension. BP was recorded with an automatic device at rest and during mental arithmetic and handgrip. When BP was recorded in the presence of the physician patients with very high ILSC values showed significantly higher values than patients with moderately high ILSC values. This difference was no longer detectable when BP was recorded in a quiet room the patients being alone. ILSC and diastolic BP at rest were significantly related (r=0.80) only when the physician was present. The percent increase in diastolic BP induced by stimulation tests was significantly related to ILSC values (r=0.91). These data suggest that pressor response to adrenergic stimulation in patients with essential hypertension is related to intracellular sodium content.

Blood Pressure↗
PubMed1983

Comparison of the antihypertensive activity of cadralazine (ISF 2469) and dihydralazine during chronic treatment.

The antihypertensive activity of a new vasodilating agent (ISF 2469) cadralazine (CD) was compared in a randomized, crossover, intrapatient study with that of hydralazine (HD) in 20 hypertensive patients whose diastolic blood pressure (BP) was greater than 95 mmHg during treatment with atenolol (AT), 100 mg 1 X daily. The initial dose of CD was 15 mg 1 X daily; after 15 days in case of poor response, the dose was increased to 20 mg 1 X daily. HD was given at a dose of 25 mg 3 X daily and was increased to 50 mg 2 X daily in case of poor response. BP values (standing) during AT were 174/108; they fell to 144/88 during CD and to 138/88 during HD. No significant difference was detected between the two drugs for both systolic and diastolic BP (supine and standing). Heart rate increased with both drugs, with a greater increase during CD. The difference was clinically nonsignificant. A total of 24 patients were enrolled, but 4 had to cease treatment because of side effects during HD. The overall prevalence of side effects was much higher during HD, especially during the first days of therapy. Also the severity of side effects was greater during HD. Our data show that CD has the same antihypertensive activity as HD with a lesser incidence of side effects and with a single dose/day administration in contrast with three administrations of HD. This can result in greater patient compliance.

Adult↗
PubMed1981

Increased intralymphocytic sodium content in essential hypertension: an index of impaired Na+ cellular metabolism.

1. The sodium concentration in lymphocytes was measured in a group of 66 normotensive subjects (40 without familial hypertension and 26 with familial hypertension), in a group of 81 patients with essential hypertension and in a group of 14 patients with secondary hypertension. 2. The mean value (+/- SD) in normotensive subjects with no history of familial hypertension was 21.9 +/- 3.1 mmol/kg wet weight, which was significantly lower (P less than 0.005) than that of normotensive subjects with familial hypertension (mean value 27.9 +/- 4.2 mmol/kg). Lymphocyte sodium concentration was significantly higher in patients with essential hypertension (33.2 +/- 3.3 mmol/kg; P less than 0.001) than in the subjects with normal blood pressure without familial hypertension. 3. In the patients with essential hypertension there was a significant correlation between lymphocyte sodium concentration and systolic (P less than 0.005), diastolic (P less than 0.001) and mean (P less than 0.001) blood pressure. In the normotensive subjects there was no correlation between the lymphocyte sodium concentration and the blood pressure. 4. The patients with secondary forms of hypertension had normal lymphocyte sodium concentration, except in the case of Conn's disease. 5. Incubation with ouabain increased lymphocyte sodium concentration in the normotensive subjects and patients with essential hypertension; the final sodium concentration was similar in the two groups. 6. When lymphocytes from normotensive subjects without familial hypertension were incubated in plasma of patients with essential hypertension there was an increase in their sodium content.

Adolescent↗
PubMed1981

Effects of a low-salt diet and of acute salt loading on blood pressure and intralymphocytic sodium concentration in young subjects with borderline hypertension.

1. Three groups of young patients with borderline hypertension were studied for a 12 months period. The first was on a free sodium diet while the second was on a low-salt diet. The third group of patients underwent acute salt loading. 2. After 12 months the group on free diet showed a significant increase of intralymphocytic sodium but no change in blood pressure was noted. Five patients who were re-checked after 24 months also had a significant increase in blood pressure. 3. Patients treated with a low-salt diet showed a significant decrease of both intralymphocytic sodium concentration and blood pressure. 4. After acute salt loading, borderline subjects with high intralymphocytic sodium showed a significant greater natriuresis whereas intralymphocytic sodium increased only in those subjects in whom it was initially normal.

Adolescent↗