Hormonal and local factors in hypertension

Omapatrilat: neurohormonal and pharmacodynamic profile when administered with furosemide

Pharmacodynamic effects of combination therapy with omapatrilat and furosemide were evaluated. Two groups of 13 healthy subjects each received furosemide 20 mg dailyfor 15 days coadministered with either placebo on days 6 to 15 or omapatrilat 10 mg on days 6 to 10 and 25 mg on days 11 to 15. In the omapatrilat group, urinary excretion of atrial natriuretic peptide increased, and greater blood pressure reductions were seen compared with placebo. Concomitant omapatrilat treatment did not affect the acute diuresis, natriuresis, and kaliuresis observed with chronic administration of furosemide. Neither effective renal plasma flow nor glomerularfiltration rate changed in either treatment group. No clinically significant safety issues were observed. Daily coadministration of omapatrilat 10 or 25 mg with furosemide 20 mg does not affect the pharmacodynamics offurosemide at steady state.

Endothelin 1-21 plasma concentrations in children and adolescents with insulin-dependent diabetes mellitus

This study is based on the hypothesis that endothelins (ETs), which are 21-amino acid peptides with vasoactive and proliferative properties, could be implicated in the development of complications of insulin dependent diabetes mellitus (IDDM) in children and adolescents. We determined plasma ET 1-21 concentrations by radioimmunoassay in 59 patients with IDDM (32 male, 27 female) and in 41 healthy siblings (20 male, 21 female) and investigated the association of ET 1-21 concentrations with age, sex, control of diabetes (expressed as % of glycosylated hemoglobin), duration of disease and presence of complications. Plasma ET 1-21 concentrations (mean +/- SEM) were 14.12 +/- 0.30 pg/ml in IDDM and 15.34 +/- 0.47 pg/ml in healthy siblings. The difference was statistically significant (p = 0.01) after controlling for age and sex by multiple logistic regression. In the group with IDDM, analysis of covariance showed duration of disease to be the only variable associated with ET 1-21 values (b = 0.2179 pg/ml/yr, p = 0.04). It is concluded that in youngsters with IDDM ET plasma concentrations are lower than in healthy controls, negatively associated with duration of the disease and not directly implicated in diabetic angiopathy.

Renal arterial and venous endothelin in hypertensive patients with or without renal artery stenosis

Immunoreactive endothelin (ir-ET) levels were measured in the renal veins and aorta of 43 untreated hypertensive patients immediately before renal angiography. None of the patients used antihypertensive medication. Twenty-seven patients had renal artery stenosis, 17 of which were unilateral and 10 bilateral. Seven of the 17 patients with unilateral renal artery stenosis had an elevated renin ratio. Of the 16 patients with essential hypertension 6 had a unilateral small kidney with a normal blood supply. Although there was a trend towards higher levels of ir-ET in patients with renal artery stenosis, no significant differences in endothelin levels (venous or arterial) were found between different groups of patients or groups of kidneys. More than 75% of kidneys extracted endothelin, there being no significant differences between groups of kidneys. In conclusion, our data demonstrate that endothelin levels and renal endothelin extraction are comparable in essential hypertension and in hypertension associated with renal artery stenosis. Whereas renal uptake or endothelin is the rule, some kidneys, however, release this peptide irrespective of the presence or absence of renal artery stenosis.

Endocrine causes of hypertension in children

Hypertension in children is not a common problem. When it is found, however, a pathologic cause can often be identified. The endocrine causes of hypertension in children are generally rare. We have reviewed the diverse and rare endocrine causes of hypertension in the pediatric population. Table 3 lists features of these conditions that assist in their diagnosis. In all patients with hypertension, a thorough history and physical examination may point to the diagnosis of endocrine or other causes of secondary hypertension. For a more detailed approach to these diagnoses, other reviews may be helpful. A phased laboratory evaluation similar to that suggested by Ogborn and Crocker facilitates in the evaluation of secondary hypertension. The critical screening tests from an endocrine point of view are plasma sodium, potassium, calcium, renin activity, and thyroid function tests, including T4, T3, and thyroid stimulating hormone. Measurement of a 24-hour urine collection for aldosterone, metanephrine, and catecholamines may be warranted if the previously mentioned studies are unrevealing. More specific studies also may be suggested by these preliminary evaluations and the history and physical examination. Further investigations should be done with the additional guidance of a pediatric endocrinologist.