Enhanced growth hormone response to clonidine in the spontaneously hypertensive rat.

Plasma concentrations of growth hormone (GH) were measured after administration of clonidine (0.5 mg/kg) to spontaneously hypertensive (SH) rats and normotensive Wistar Kyoto controls. All rats were pretreated with reserpine (10 mg/kg). The GH response to clonidine was significantly higher in SH rats than in controls, indicating that in SH rats the responsiveness of post-synaptic alpha-adrenergic structures in the hypothalamus may be increased.