Effect of Clonidine on Renal Sodium Handling in Spontaneously Hypertensive Rats

Abstract

Abstract. Up-regulation of kidney α 2 -adrenoceptor expression has been implicated in the development of hypertension in spontaneously hypertensive rats (SHR). This study was carried out to evaluate renal sodium excretion in response to clonidine administration in SHR and control normotensive Wistar-Kyoto (WKY) rats. SHR and WKY rats (12-week-old) were placed in metabolic cages for 4 days: the first 2 days in control conditions and the following 2 days under oral clonidine treatment (100 μg/kg body weight). Clonidine produced a similar reduction in systolic blood pressure values in SHR and WKY rats, although SHR remained hypertensive. At the end of the study SHR and WKY rats presented similar noradrenaline plasma levels. However, noradrenaline kidney tissue levels were significantly higher in SHR compared to WKY rats. Under control conditions, SHR presented lower urine flow compared to WKY rats. Clonidine produced a significant decrease in urine flow in WKY rats but not in SHR. Furthermore, clonidine also produced a significant reduction in urinary sodium, potassium, and creatinine excretion in WKY rats, but had no effect in SHR. In conclusion, in SHR the reduction in systolic blood pressure and sympathetic activity produced by clonidine was not accompanied by a decrease in urine volume and sodium excretion.

Role of the renal sympathetic nerves in renal sodium/potassium handling and renal damage in spontaneously hypertensive rats

“…Furthermore, a previous study using isolated perfused kidneys from SHRs revealed an intrinsic renal abnormality in sodium excretion that may contribute to the maintenance of hypertension in SHR ( 25 ). Renal sympathetic nerves and circulating catecholamine are involved in the regulation of sodium and water excretion in the kidney ( 26 ). In the present study, a significant change to sodium excretion was observed following RD.…”

Urinary profile of catecholamines and metabolites in Parkinson patients with deep brain stimulation

“…The assay of l ‐DOPA, monoamines (DA and noradrenaline) and DA metabolites (DOPAC, HVA and 3‐MT) in urine samples was performed by means of high‐performance liquid chromatography with electrochemical detection, as previously described . In brief, aliquots of 5 μl of acidified urine were placed in 5‐ml conical‐based glass vials with 50 mg alumina, and the pH of the samples was adjusted to pH 8.6 by the addition of Tris buffer.…”