Biomedical subjects

N De Luca

Publications and source records attributed to N De Luca.

At least 73 records · Page 4Linked to original sources

PubMed1986

Carotid baroreceptor unloading decreases plasma atrial natriuretic factor in hypertensive patients.

Atrial natriuretic factor (ANF) release is known to be regulated by distension of the atrial wall; other factors affecting ANF secretion have not yet been defined. In order to evaluate the effects of the reflex activation of the sympathetic nervous system on ANF plasma levels, in 11 patients with essential hypertension progressive deactivation of carotid baroreceptors was induced by 4-min graded increases in external neck tissue pressure. Carotid sinus hypotension induced progressive increases in blood pressure (BP), heart rate (HR) and forearm vascular resistance (FVR), while plasma renin activity and catecholamine concentrations did not change significantly. Despite the lack of changes in right atrial pressure during this manoeuvre, plasma ANF levels showed a progressive and significant reduction, which was correlated with the increase in FVR. Although a contribution by other factors cannot be ruled out, our data suggest that the reflex activation of sympathetic nervous system is associated with reduced ANF release, independent of changes in atrial pressure.

Adult↗

PubMed1985

Cardiac hypertrophy and arterial distensibility in essential hypertension.

Echocardiographic determinations, left ventricular mass-volume ratio (M/V), left ventricular end-systolic stress (ESS), carotidofemoral pulse wave velocity (PWV), and brachial artery compliance (BAC), deduced from pulsed Doppler measurements and from the Bramwell-Hill equation, were evaluated in 20 patients with sustained essential hypertension in comparison with 20 control subjects of the same age and sex. In hypertensive patients, M/V ratio, ESS, and PWV were significantly increased while BAC was reduced. In the overall population, ESS was directly correlated with PWV (r = 0.73), and M/V ratio was significantly correlated with PWV (r = 0.60), BAC (r = -0.70), and systolic arterial pressure (r = 0.71). No comparable results were observed with diastolic arterial pressure. PWV was unchanged after cadralazine, a dihydralazine-like substance, and was decreased with the same blood pressure reduction following nitrendipine, a new calcium-blocking agent. These results suggest that: (1) the distensibility of large arteries plays an important role in the maintenance of cardiac hypertrophy in hypertension, and (2) antihypertensive drugs may act differently on arterial distensibility with possible consequences on ESS and reversion of left ventricular hypertrophy.

Adult↗

PubMed1985

Participation of endogenous catecholamines in the regulation of left ventricular mass in progeny of hypertensive parents.

To investigate whether adrenergic activity is a determinant of left ventricular hypertrophy in human hypertension, in each of 10 normotensive subjects with two hypertensive parents we have examined the relationship between changes in echocardiographic parameters of left ventricular anatomy and those in circulating catecholamine levels induced by three, 3 week periods of different sodium and potassium intakes. A high sodium-normal potassium regimen induced a significant reduction in upright plasma norepinephrine (from 599 +/- 89 to 379 +/- 45 pg/ml, p less than .01) and in posterior wall (PWT) and interventricular septal (IVST) thickness, as well as in the left ventricular mass index (LVMi). Changes in upright plasma norepinephrine concentrations correlated with those in IVST (r = .822, p less than .01) and in LVMi (r = .833, p less than .01). A low sodium-normal potassium diet resulted in increases in supine and upright plasma norepinephrine levels (from 356 +/- 44 to 488 +/- 89 pg/ml, p less than .001; and from 565 +/- 42 to 744 +/- 33 pg/ml, p less than .01) as well as increases in IVST and LVMi (from 97 +/- 7 to 107 +/- 7 g/m2, p less than .001). The changes in norepinephrine levels in supine and upright subjects correlated with changes in IVST (r = .836, p less than .01 and r = .796, p less than .01) and in LVMi (r = .931, p less than .001 and r = .947, p less than .001). No significant change in plasma catecholamine concentrations or in PWT, IVST, or LVMi was detected after a low sodium-high potassium regimen.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1985

Regulation of left ventricular mass by endogenous catecholamines in hypertensive progeny.

In 10 normotensives with both parents hypertensive, the relationship between changes in echocardiographic parameters of left ventricular anatomy and those in circulating catecholamine levels induced by three 3-week periods of different sodium and potassium intakes were examined. A high-sodium normal-potassium regimen reduced upright plasma norepinephrine (P less than 0.01), posterior wall thickness (PWT) and interventricular septal thickness (IVST) as well as the left ventricular mass index (LVMi). Changes in upright plasma noreprinephrine correlated with those in IVST (r = 0.822, P less than 0.01) and in LVMi (r = 0.833, P less than 0.01). A low-sodium normal-potassium diet increased supine (P less than 0.001) and upright (P less than 0.01) plasma norepinephrine as well as the IVST and LVMi. The changes in supine and upright norepinephrine levels correlated with changes in IVST (r = 0.836 and r = 0.796 respectively, both P less than 0.01) and in LVMi (r = 0.931 and r = 0.947 respectively, both P less than 0.001). No significant change in any of the above parameters was detected after a low-sodium high-potassium regimen. These findings indicate that in hypertensive progeny catecholamines may play a role in the physiological regulation of left ventricular mass (LVM).

Adult↗

PubMed1984

Effect of acebutolol on left ventricular hemodynamics and anatomy in systemic hypertension.

In 18 patients with mild or moderate essential hypertension who responded favorably to acebutolol antihypertensive therapy, echocardiography (echo) was performed in the basal condition and after 6 and 12 months of follow-up. Acebutolol induced a significant decrease in blood pressure (BP), from a basal value of 167 +/- 3/105 +/- 2 mm Hg to 138 +/- 5/90 +/- 2 mm Hg after 6 months (p less than 0.01) and to 134 +/- 3/91 +/- 3 mm Hg after 1 year (p less than 0.01), and in heart rate, from 75 +/- 3 to 63 +/- 2 beats/min after 6 months (p less than 0.01) and to 63 +/- 2 beats/min after 1 year (p less than 0.01). The decrease in BP was achieved through a decrease in cardiac output from 6.3 +/- 0.28 to 5.3 +/- 0.25 liters/min after 6 months (p less than 0.05) and to 5.32 +/- 0.2 liters/min after 1 year (p less than 0.05), which resulted from a reduction in heart rate; stroke volume did not show significant change during the treatment and left ventricular (LV) performance was improved. There was a parallel decrease in LV posterior wall and ventricular septal thicknesses and estimated LV mass. In patients with LV hypertrophy, the change in mass was significantly correlated with the change in heart rate both after 6 and 12 months of therapy (r = 0.6234, p less than 0.05 and r = 0.7121, p less than 0.05 after 6 and 12 months, respectively).

Acebutolol↗

PubMed1984

QT/QS2 ratio as an index of autonomic tone changes.

The effects of changes in sympathetic tone on QT/QS2 ratio were studied in 10 healthy subjects aged 21 to 24 years. The subjects underwent a bicycle ergometer exercise, a tilt test, a decrease in carotid transmural pressure induced by means of pneumatic neck chamber, an i.v. injection of phenylephrine. A phonocardiogram and ECG were simultaneously recorded at a paper speed of 100 mm/s to evaluate QT and QS2 intervals in each test. In basal conditions, the QT/QS2 ratio was less than 1, whereas it increased progressively during the physical exercise and became greater than 1 at peak exercise. Both the upright position and the increase in neck-tissue pressure induced a significant increase in the QT/QS2 ratio as compared with the basal values, whereas i.v. administration of phenylephrine reduced significantly the QT/QS2 ratio. These results demonstrate that those stimuli which induce a rise in adrenergic activity may increase the QT/QS2 ratio. In contrast, the reflex inhibition of the adrenergic activity induced by phenylephrine is accompanied by a reduction in QT/QS2 ratio. Therefore, the QT/QS2 ratio might represent a reliable index of sympathetic cardiac tone.

Adult↗

PubMed1984

Relationships between left ventricular mass and clinical, biohumoral and hemodynamic parameters in human hypertension.

The relationships between left ventricular mass (LVM), assessed by echocardiography, and several biohumoral and hemodynamic parameters were studied in 63 mild or moderate hypertensive patients and in an age-matched group of 23 normotensive subjects. In hypertensive patients, but not in normotensives, LVM index was significantly correlated with beta-adrenoceptor responsiveness, as evaluated by the chronotropic response to isoproterenol ( CD25 ) (r = 0.525, p less than 0.001) and with the 24-hour catecholamine urinary output (r = 0.485, p less than 0.001). Both CD25 and the catecholamine urinary output were significantly higher in the hypertensives as compared with the normotensive subjects. Moreover, left ventricular wall thickness (septum + posterior wall) was significantly correlated with CD25 and urinary catecholamines only in hypertensive patients. No significant correlation was found between LVM or wall thickness and body surface area, age, blood pressure, heart rate, cardiac output, total peripheral resistance and left ventricular systolic wall stress, whereas CD25 was correlated with urinary catecholamines only in hypertensive patients (r = 0.606, p less than 0.001). These results seem to support the hypothesis that an elevated adrenergic tone may exert a permissive role in the development of left ventricular hypertrophy in human hypertension.

Adolescent↗

PubMed1983

Predictability of antihypertensive efficacy of selective beta 1 blockers.

The possibility that hemodynamic and biohumoral factors may help predict the antihypertensive effectiveness of selective beta 1 blockers was investigated. The effects of 3 wk of treatment with two selective beta 1 blockers, metoprolol and atenolol, were observed in 54 patients with mild or moderate essential hypertension. No significant difference between the hemodynamic effects of the two drugs was found. The percent fall in systolic blood pressure induced by the two correlated strongly with the pretreatment values of the chronotropic response to isoproterenol and with the pretreatment values of cardiac output, heart rate, and plasma renin activity (PRA). There was no correlation between the decrease in systolic blood pressure induced and initial 24-hr urinary catecholamine output, total peripheral resistance, and plasma aldosterone. Percent fall in diastolic blood pressure correlated only with the pretreatment levels of PRA. Our results support the view that the hypotensive effect of beta 1 blockers are predictable on the basis of the pretreatment values of chronotropic response to isoproterenol, PRA, heart rate, and cardiac output.

Adult↗

PubMed1983

Haemodynamic and clinical effects of long-term treatment of essential hypertension with captopril.

Captopril, an orally active inhibitor of angiotensin converting enzyme, was administered for 12 months to 20 patients with mild or moderate essential hypertension who initially responded favourably to this pharmacological treatment. Captopril induced a significant reduction in blood pressure which remained unmodified throughout the study. This fall in blood pressure was mainly due to a significant decrease in total peripheral vascular resistance, since no change in cardiac output was observed. Simultaneously, there was no significant change in left ventricular anatomy and performance evaluated by echocardiographic technique.

Adult↗

PubMed1983

Valsalva maneuver in the assessment of baroreflex responsiveness in borderline hypertensives.

Baroreceptor function was assessed by (1) the reflex response during Valsalva maneuver, (2) phenylephrine injection, and (3) increase in neck tissue pressure by a neck-chamber in 15 borderline hypertensives (B) and in 15 age-matched normotensives (N). B responded to the fall in blood pressure, occurring in phase II of Valsalva maneuver, with an increase in blood pressure and a decrease in the R-R interval of comparable extent to those observed in normals. On the contrary, in phase IV B showed a depressed heart rate reflex response whether evaluated by the slope of the regression line obtained by plotting the R-R interval versus the systolic blood pressure (slope: B = 6.1 +/- 3.3; N = 35.6 +/- 7, p less than 0.005) or by the change in R-R interval (delta R-R interval: B = 67.5 +/- 37 ms; N = 319 +/- 55 ms, p less than 0.005). On the other hand, both phenylephrine injection and neck-chamber procedure showed an impaired baroreflex responsiveness in B. A linear positive correlation was found between the individual values of the slopes obtained during phase IV of Valsalva maneuver and after phenylephrine injection both in N (r = 0.944, p less than 0.001) and in B (r = 0.84, p less than 0.001). Finally, a linear positive correlation was found between the individual values of the slopes obtained by the phenylephrine technique and the corresponding maximum percent change in R-R interval during phase IV of the Valsalva maneuver both in normals and in hypertensives. In conclusion, overshoot bradycardia during Valsalva maneuver seems to show enough specificity in the evaluation of baroreflex responsiveness to be employed in epidemiological studies in this area.

Adolescent↗

PubMed1983