Cerebrospinal fluid angiotensin II immunoreactivity is not derived from the plasma.
To elucidate whether the presence of angiotensin II immunoreactivity (ANG II-ir) in the cerebrospinal fluid (CSF) of the dog is in part due to passage of the peptide across the CSF-blood-brain barrier, [Ile5] angiotensin II (ANG II) was infused intravenously for 7 days in conscious, trained dogs at a rate of 10 micrograms/kg/day. Mean arterial pressure (MAP) and heart rate were monitored each day, and samples of arterial blood and CSF (with a catheter secured into the cisterna magna) were drawn at regular intervals for determination of catecholamine levels, ANG II-ir, and electrolyte levels. Within 2 days after ANG II infusion, MAP stabilized at 35 +/- 1 mm Hg (mean +/- SE, p less than 0.001) above control values. The hypertension was associated with bradycardia, suppressed plasma renin activity, and a fall in both plasma and CSF Na+ concentrations. These changes coincided with a considerable and sustained decrease in the levels of plasma and CSF norepinephrine. On the other hand, levels of epinephrine and K+ in the two compartments remained unchanged. Although concentration of ANG II-ir in plasma was augmented markedly (368% above control values, p less than 0.001), ANG II-ir in the CSF remained within the low values measured in the control period.(ABSTRACT TRUNCATED AT 250 WORDS)
D000804:Angiotensin II / Q000008:administration & dosage / Q000134:cerebrospinal fluid* / Q000276:immunology; D000818:Animals; D001835:Body Weight; D004285:Dogs; D006400:Hematocrit; D006978:Hypertension, Renovascular / Q000097:blood; D007263:Infusions, Parenteral; D009638:Norepinephrine / Q000097:blood
D000804:Angiotensin II; D009638:Norepinephrine