PMID- 6121811
OWN - NLM
STAT- MEDLINE
DCOM- 19820621
LR  - 20191031
IS  - 0144-1795 (Print)
IS  - 0144-1795 (Linking)
VI  - 1
IP  - 2
DP  - 1981 Mar
TI  - Studies on the pre- and postjunctional activities of alpha-adrenoreceptor 
      agonists and their cardiovascular effects in the anaesthetized rat.
PG  - 157-69
AB  - 1 The selectivity of a number of agonists for peripheral alpha 1- and alpha 2- 
      adrenoreceptors was determined and related to their cardiovascular effects in 
      pentobarbitone-anaesthetized rats. 2 In isolated tissues, presynaptic alpha 2- 
      and postsynaptic alpha 1-adrenoreceptor activity was determined on the rat vas 
      deferens and anococcygeus muscle respectively. Xylazine, guanabenz, guanoxabenz 
      and guanfacin were more selective, whilst lofexidine, tiamenidine, naphazoline, 
      oxymetazoline and St 91 were less selective than clonidine for presynaptic alpha 
      2-adrenoreceptors. 3 The anococcygeus muscle of the pithed rat was used to 
      determine the alpha-adrenoreceptor selectivity of the compounds in vivo. The 
      selectivities were similar to those obtained in vitro. 4 Following intravenous 
      administration to pentobarbitone-anaesthetized rats guanabenz and guanfacin 
      caused small transient pressor responses and a prolonged secondary hypotension. 
      In contrast oxymetazoline and St 91 produced marked initial pressor responses and 
      the secondary reduction in blood pressure was absent. Clonidine and tiamenidine 
      produced marked initial pressor responses followed by secondary hypotensive 
      effects. All compounds reduced heart rate. 5 Intracerebroventricular (i.c.v.) 
      administration of clonidine, guanabenz and guanfacin elicited falls in blood 
      pressure and heart rate. In contrast blood pressure was either unaffected or 
      elevated following i.c.v. administration of St 91, oxymetazoline and tiamenidine. 
      6 It is concluded that in the normotensive rat, central alpha 2-adrenoreceptors 
      play a major role in the hypotensive effects of clonidine and related compounds.
FAU - Doxey, J C
AU  - Doxey JC
FAU - Frank, L W
AU  - Frank LW
FAU - Hersom, A S
AU  - Hersom AS
LA  - eng
PT  - Journal Article
PL  - England
TA  - J Auton Pharmacol
JT  - Journal of autonomic pharmacology
JID - 8106455
RN  - 0 (Adrenergic alpha-Agonists)
SB  - IM
MH  - Adrenergic alpha-Agonists/*pharmacology
MH  - Anesthesia
MH  - Animals
MH  - Hemodynamics/*drug effects
MH  - In Vitro Techniques
MH  - Injections, Intravenous
MH  - Injections, Intraventricular
MH  - Male
MH  - Muscle Contraction/drug effects
MH  - Muscle, Smooth/drug effects
MH  - Neuromuscular Junction/*drug effects
MH  - Rats
MH  - Spinal Cord/physiology
MH  - Vas Deferens/drug effects
EDAT- 1981/03/01 00:00
MHDA- 1981/03/01 00:01
CRDT- 1981/03/01 00:00
PHST- 1981/03/01 00:00 [pubmed]
PHST- 1981/03/01 00:01 [medline]
PHST- 1981/03/01 00:00 [entrez]
AID - 10.1111/j.1474-8673.1981.tb00508.x [doi]
PST - ppublish
SO  - J Auton Pharmacol. 1981 Mar;1(2):157-69. doi: 10.1111/j.1474-8673.1981.tb00508.x.