The effects of genetic factors on selected indicators of the activity of the sympathoadrenal system and the renin-angiotensin-aldosterone system in twins.

BACKGROUND: There are numerous data indicating a significant role of the sympathoadrenal system and the reninangiotensin- aldosterone system in the regulation of blood pressure and the pathogenesis of essential hypertension. However, the genetic background of essential hypertension remains unclear. AIM: To determine the effects of genetic factors on selected indicators of the activity of the sympathoadrenal system and the renin-angiotensin-aldosterone system in twins. METHODS: We studied 39 monozygotic twin pairs (age 33+/-7 years) and 37 same-gender dizygotic twin pairs (age 36+/-7 years). We measured blood and urine adrenaline (A), noradrenaline (NA), dopamine (DA) and aldosterone (ALD) levels, as well as plasma renin activity (PRA) and serum angiotensin-converting enzyme (ACE) activity. Parameters of the genetic models for age- and gender-adjusted data were estimated by model fitting and path analysis technique using LISREL 8. RESULTS: The effects of genetic factors on the variability of blood and urine catecholamine levels were 69% and 65% for A, 42% and 76% for NA, and 58% and 40% for DA, respectively. We also found shared environmental components for blood NA (28%) and urine DA (17%). Genetic factors accounted for 36% of the variability of PRA and 80% of the variability of ACE. ALD levels were related only to environmental factors (including a shared environmental component, estimated at 25%, for urine ALD). CONCLUSIONS: We found significant effects of genetic factors on the activity of the sympathoadrenal system, as indicated by blood and urine catecholamine levels. We also found the effect of genetic factors on PRA and ACE, but not on aldosterone levels.

Do catecholamines influence the level of plasma leptin in patients with phaeochromocytoma?

The relationship between plasma leptin and catecholamine concentrations during chronic and acute catecholamine excess is studied. Patients with phaeochromocytoma, divided according to gender, were examined under basal conditions (n = 18) and at selected time-points during surgical removal of the tumour (n = 12). Appropriate controls were used (n = 23) for the basal study. Plasma leptin was determined by radioimmunoassay (RIA) and plasma noradrenaline (NA) and adrenaline (A) by high-performance liquid chromatography (HPLC). Statistical evaluation employed Student's t-test, Wicoxon test and Spearman's correlation coefficient. Gender-related differences in plasma leptin in normal subjects was confirmed, and these were maintained in the patients. Phaeochromocytoma patients had normal plasma leptin levels in the basal state and decreased levels following the massive catecholamine surge provoked by surgery. Plasma leptin concentration did not correlate with plasma NA or A in either group studied. In the patients with phaeochromocytoma, acute but not chronic catecholamine excess affected plasma leptin, suggesting a role for sympathetic activity in modulating leptin release.

Do catecholamines influence the level of plasma leptin in patients with phaeochromocytoma?

The relationship between plasma leptin and catecholamine concentrations during chronic and acute catecholamine excess is studied. Patients with phaeochromocytoma, divided according to gender, were examined under basal conditions (n=18) and at selected time-points during surgical removal of the tumour (n=12). Appropriate controls were used (n=23) for the basal study. Plasma leptin was determined by radioimmunoassay (RIA) and plasma noradrenaline (NA) and adrenaline (A) by highperformance liquid chromatography (HPLC). Statistical evaluation employed Student's t-test, Wicoxon test and Spearman's correlation coefficient. Gender-related differences in plasma leptin in normal subjects was confirmed, and these were maintained in the patients. Phaeochromocytoma patients had normal plasma leptin levels in the basal state and decreased levels following the massive catecholamine surge provoked by surgery. Plasma leptin concentration did not correlate with plasma NA or A in either group studied. In the patients with phaeochromocytoma, acute but not chronic catecholamine excess affected plasma leptin, suggesting a role for sympathetic activity in modulating leptin release.