Differing noradrenaline kinetics in essential hypertension and depressive illness, two diseases in which the plasma concentration of noradrenaline is sometimes elevated

Blood pressure and heart rate variability and baroreflex sensitivity in white-coat, masked, and sustained hypertension

We investigated blood pressure (BP) and heart rate variability and baroreflex sensitivity (BRS) in white-coat, masked and sustained hypertension in untreated patients (n = 645). Normotension and white-coat, masked, and sustained hypertension were defined according to the clinic (cutoff 140/90 mmHg) and 24-h ambulatory (130/80 mmHg) BPs. The Finometer device recorded beat-to-beat finger BP and electrocardiograms in the supine and standing positions for the computation of frequency-domain power-spectral BP and heart rate variability indexes and BRS. In multivariate analysis, BP variability indexes in the supine position differed significantly (P < 0.0001) for both low-frequency (LF) and high-frequency (HF) components and the LF/HF ratio, with the lowest LF and HF power and highest LF/HF ratio in white-coat hypertension (n = 28), the highest LF and HF power and lowest LF/HF ratio in sustained hypertension (n = 198), and intermediate values in normotension (n = 189) and masked hypertension (n = 230). These differences diminished in the standing position, being significant (P < 0.0001) only for the LF component variability. The LF/HF ratio in BP in the supine position decreased with advancing age in normotension and sustained hypertension (P ≤ 0.03) but not white-coat or masked hypertension (P ≥ 0.12). For heart rate variability, a significant difference was observed only for the LF component in the supine position (P = 0.0005), which was lowest in white-coat hypertension. BRS in masked and sustained hypertension was significantly (P ≤ 0.0001) lower than that in normotension in both supine and standing positions and decreased with advancing age (P ≤ 0.0001). In conclusion, masked, but not white-coat, hypertension showed similar patterns of, but slightly less severe, changes in BP and heart rate variability and BRS to sustained hypertension.

Uric acid and hypertension in adolescents

Hypertension is the most common form of cardiovascular disease. Although it is less common in adolescents than in adults, hypertension and the associated organ damage can and often does begin early in life. Consequently, for many with high blood pressure (BP), measures directed at the long-term prevention of cardiovascular morbidity may need to be started in adolescence to achieve maximal effectiveness. This article discusses some of the problems unique to hypertension in the young, as well as recent discoveries regarding the likely role played by increases in serum uric acid level in the development of adolescent-onset essential hypertension.

Sexual diergism of baseline plasma leptin and leptin suppression by arginine vasopressin in major depressives and matched controls

Leptin inhibits appetite by activating several neuroendocrine systems, including the hypothalamo-pituitary-adrenal cortical (HPA) axis. In turn, chronically elevated glucocorticoids increase circulating leptin. HPA axis hyperactivity occurs in 30-50% of patients with major depression, but the few prior reports of leptin measurements in this illness have shown inconsistent results. We, therefore, measured plasma leptin in 12 female and 8 male unipolar major depressives and 12 female and 8 male individually matched normal controls administered low-dose physostigmine (PHYSO) and arginine vasopressin (AVP) to stimulate the HPA axis. The subjects underwent four test sessions 5-7 days apart: PHYSO (8 microg/kg IV); AVP (0-08 U/kg IM); PHYSO+AVP; and saline control. Serial blood samples were taken before and after pharmacologic challenge and analyzed for leptin, ACTH(1-39), cortisol and AVP. Estradiol and testosterone also were measured at each test session. PHYSO and AVP produced no side effects in approximately half the subjects and predominantly mild side effects in the other half, with no significant patient-control differences. Correlations between side effects (absent or present) after PHYSO or AVP and the corresponding leptin responses were non-significant in all groups. Baseline plasma leptin concentrations (mean+/-S.D.) were significantly higher in the female patients compared to the female controls (22.5+/-13.9 ng/ml vs. 12.3+/-9.7 ng/ml), whereas they were similar in the male patients and the male controls (3.9+/-1.4 ng/ml vs. 3.6+/-2.0 ng/ml). Leptin concentrations following PHYSO remained unchanged from baseline, indicating that the short-lived ACTH and cortisol increases produced by PHYSO did not affect leptin secretion. In contrast, AVP administration, while also increasing ACTH and cortisol, significantly suppressed leptin, more so in the women than in the men. Baseline leptin and the leptin decrease after AVP were moderately positively correlated with the Hamilton Depression Scale 'somatization' factor in the female patients (r=0.50) and more strongly correlated with the 'mood-depression' factor in the male patients (r=0.81). These findings indicate a sexual diergism (functional sex difference) in plasma leptin measures between major depressives and matched normal controls.

Norepinephrine clearance, chromogranin A and dopamine beta hydroxylase in renal failure

Plasma norepinephrine (NE) levels are normal or elevated in patients with renal failure even though uremia often damages the sympathetic nerves that release NE. We infused 3H-NE into subjects with normal, mildly depressed, or absent renal function. 3H-NE clearance was depressed 20% in mild renal failure and 40% in patients on hemodialysis. The calculated rate of NE release into plasma was low in uremics even though their plasma NE was normal. Dopamine beta hydroxylase (D beta H) and chromogranin A are released from sympathetic nerve endings along with NE. D beta H levels were low in uremia and D beta H levels doubled following hemodialysis. Chromogranin A levels were very high in uremics and increased slightly following hemodialysis. Plasma clearance of both NE and chromogranin A appears low in renal failure. The calculated rate of NE release is diminished in uremics, which is in accord with reports of autonomic neuropathy in these patients.

Age, race, diagnosis, and sodium effects on the pressor response to infused norepinephrine

We studied the blood pressure responses to infused norepinephrine in 34 normotensive and 21 unmedicated subjects with essential hypertension. The two groups were similar in age, relative body weight, and urinary electrolyte excretion. Patients were studied on two extremes of dietary salt (200 mEq Na and 10 mEq Na per day). The dose-response curves were highly linear (p less than 0.00001) for both systolic and diastolic blood pressures. There was no evidence for an increased sensitivity to infused norepinephrine among the hypertensive subjects. On the other hand, older subjects had steeper slopes (p less than 0.005). Subjects on a high salt diet had steeper slopes than those on low salt diets (p less than 0.0025); this trend was especially apparent among blacks (p less than 0.005). Black and white hypertensive subjects responded to the high salt diet in opposite fashion: The blacks showed an increased pressor sensitivity (p less than 0.05), whereas the whites demonstrated a nonsignificant decreased pressor sensitivity. These results indicate that age, race, and salt effects must be meticulously controlled in studies of sympathetic nervous system physiology.