Alterations in plasma and cerebrospinal fluid norepinephrine and angiotensin II during the development of renal hypertension in conscious dogs.

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Abstract
The levels of norepinephrine (NE), epinephrine (E), and angiotensin II immunoreactivity (AIIir) in plasma and in cerebrospinal fluid (CSF) were measured in eight conscious dogs before and during a 28-day period in the development of two-kidney, one clip (2K1C) hypertension produced by a two-step procedure. The early phase (less than 7 days) of hypertension following partial constriction of the renal artery was accompanied by tachycardia and increases in concentrations of NE and AIIir in both plasma and CSF; E did not change. One week later blood pressure remained elevated (107 +/- 2 after vs 88 +/- 2 mm Hg before clipping, p less than 0.05), but other variables returned to control values. Occlusion of the partially constricted renal artery caused severe hypertension that was initially associated with a transient decrease in levels of NE in both plasma and CSF and a sustained rise in plasma and CSF concentrations of AIIir that persisted for as long as 2 weeks after the second operation. None of these effects was seen in nine sham-operated dogs. Since activation of the renal pressor system is associated with time-related changes in the concentrations of NE and AII in both plasma and CSF, these observations indicate early involvement of both sympathetic and renin-angiotensin systems in the pathogenesis of renovascular hypertension.