Prolonged effects of p-chlorophenylalanine on the blood pressure of conscious normotensive and DOCA/saline hypertensive rats.
1. In deoxycorticosterone acetate (DOCA) saline hypertensive rats a single dose of p-chlorophenylalanine methylester (PCPAME) (400 mg/kg i.p.) produced a significant fall in blood pressure (20-43 mmHg) which lasted for at least 8 days and was accompanied by a parallel depletion of brain stem 5-hydroxytryptamine (5-ht) but not of noradrenaline (NA). 2. In normotensive rats single doses of PCPAME (200 and 400 mg/kg i.p.) produced a significant hypotension (15-20 mmHg) after a latent period of 5 days. An initial pressor response (12 mmHg) was observed at the higher dose level only on day 3. 3. The hypotensive response to PCPAME (200 mg/kg i.p.) in normotensive rats was not modified by pretreatment with 5,6-dihydroxytryptamine (5,6-DHT; 50 mug i.c.v.) or 6-hydroxydopa (6-ohda; 3 X 250 mug intracerebroventricularly). 4. It is concluded that the hypotensive response to PCPAME in normotensive rats in independent of brain stem depletion of 5-HT and is probably not mediated by the formation of a false transmitter substance acting via central noradrenergic inhibitory pathways. The mechanism involved in the antihypertensive response to PCPAME in DOVA/saline hypertensive rats has yet to be defined.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D003900:Desoxycorticosterone; D010134:Fenclonine / Q000494:pharmacology*; D006892:Hydroxydopamines / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D008526:Medulla Oblongata / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D011149:Pons / Q000378:metabolism; D051381:Rats; D012701:Serotonin / Q000378:metabolism; D013997:Time Factors
D006892:Hydroxydopamines; D012701:Serotonin; D003900:Desoxycorticosterone; D010134:Fenclonine; D009638:Norepinephrine