Influence of alpha 1-adrenoceptor blockade and/or 5-HT1A agonism on blood pressure and heart rate at rest and during exercise in hypertensive dogs.
1. Antihypertensive effects resulting from alpha 1-adrenoceptor blockade and stimulation of central nervous 5-HT1A receptors were compared with the effects arising from stimulation of 5-HT1A receptors alone during arterial hypertension. 2. Urapidil and 5-methyl-urapidil were less effective in decreasing arterial blood pressure than the lowest dose of the selective 5-HT1A receptor agonist, flesinoxan. After the higher dose of urapidil, a certain dampening of barareceptor reflex was found which was also seen with flesinoxan. 3. Flesinoxan was the only drug which did not reduce the exercise-induced increase in systolic arterial blood pressure. 4. Stimulation of 5-HT1A receptors alone, which is assumed to occur with flesinoxan, exerted antihypertensive activity only at low doses, without inducing reflex tachycardia at rest. 5. Only the combined effects of alpha 1-adrenoceptor blockade and 5-HT1A receptor stimulation, as assumed to occur with urapidil and 5-methyl-urapidil, lead to both a decrease in arterial blood pressure at rest and during exercise.
Department of Cardiovascular Pharmacology, University of Vienna, Austria.
J G
JG
Grohs
S
S
Huber
G
G
Fischer
G
G
Raberger
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects*; D006973:Hypertension / Q000503:physiopathology*; D005082:Physical Exertion / Q000502:physiology*; D011985:Receptors, Serotonin / Q000187:drug effects*
D000317:Adrenergic alpha-Antagonists; D011985:Receptors, Serotonin