The Action of Ergotamine on the Chemical and Mechanical Reflexes from the Carotid Sinus Region.

Abstract

ROTHLIN showed in 1923 that the fall in blood pressure caused by stimulation of the depressor nerves in, the rabbit was greatly diminished by ergotamine. HEYMANS and REGNIERS (1929) studied the effect of ergotamine on the sinus reflexes and found that while the vasomotor reflexes from the sinus region were suppressed by ergotamine (0.25 nig ergotamine tartrate pr kg) in the dog, the cardio-inhibitory reflexes persisted or were even temporarily reinforced. Using smaller doses, 0.1-0. I 5 mg/kg in the cat, WRIGHT (1930) was able t o state that the vasomotor reflexes from the sinus were abolished, though the dose of ergotamine was not sufficient to suppress the effect of injected adrenaline or else block the peripheral vasomotor mechanism. On the other hand central asphyxia was still active i n producing a rise in blood-pressure. He therefore drew the conclusion that ergotamine inhibited the central transmission of impulses on the afferent side of the vasomotor centre. HEYMANS, REGNIERS and BOUCKAERT (1930), in a continuation of their previous study, showed that when 0.26 mg ergotamine tartrate per kg was injected into a dog, the head of which was perfused by another dog, occlusion and opening of the common carotids leading to the perfused head had no effect on the blood pressure of the rest of the body. The animal was in this case insensitive even t o injected adrenaline, however. 04 the other hand a similar dose of ergotarnine injected into the

The Action of Ergotamine on the Intracranial Venous Pressure and on the Cerebral Venous Outflow of the Dog

“…1). Sometimes this action was slightly potentiated as previously observed by Hartman (1915), Woods, Nelson, and Nelson (1932), Herwick, Linegar and Koppanyi (1939), and Von Euler and Schmiterlow (1944). The renal vasoconstrictor response to adrenaline was unaltered after ergotamine, and the nasal vasoconstriction only partially reduced ( Fig.…”

Changes in penile volume during some cardiovascular reflexes and reactions in rabbit

“…The latter mixture was sometimes followed by 100 % 0,. (Euler & Schmiterlow 1944). infusion of I5x lo-' M KCN or rapid i.v.…”

“…(Euler & Soderberg 1952) and central pharmacological elimination of baroreflexes by ergotamine (0.7-1.4 pmol/kg i.v.) (Euler & Schmiterlow 1944).…”

Role of Some Biogenic Substances in Migraine and Relevant Mechanism in Antimigraine Action of Ergotamine‐studies in an Experimental Model for Migraine

“…Dalessio and his co-workers (see 85,[89][90][91] have suggested that the antimigraine effect of methysergide may be due to a suppression of circulatory reflex. Since the latter effect is also exhibited by ergotamine, [36][37][38] we decided to compare the vascular effects of the drug with those on the reflex pressor responses to bilateral occlusion of common carotid arteries in intact (without vagosympathectomy and sinus nerve section) anesthetized dogs. In these dogs, ergotamine (1-32m.g/kg) did have slight pressor effect, and in higher doses antagonized the pressor response to carotid occlusion (see Fig.…”

“…However, its other pharmacological actions, e.g. a-adrenolytic, antiserotinin and circulatory reflex-inhibitory properties [33][34][35][36][37][38][39][40] may also contribute significantly particularly in view of the suggested incrimination of noradrenaline, 5-HT [18][19][20][21][22][23][24][25][26][27] and reflex vasomotor disfunction 41,42 in the pathophysiology of migraine. Moreover, the potent antiserotonin and very feeble vasoconstrictor properties of methysergide 43 and the remarkable antiserotonin and antihistaminic character of cyproheptadine 44 and BC-105 45 have led to the belief that the common antiserotonin action is largely re-sponsible for the therapeutic effectiveness of antiserotonin-antimigraine drugs.…”