Ganglionic Blocking Agent Hexamethonium Research Articles

Sympathetic innervation of the coeliac artery from a teleost, gadus morhua

1. The sympathetic innervation of the cod coeliac artery has been investigated. An isolated nerve-artery in vitro preparation, including the coeliac artery, the splanchnic nerve and parts of the sympathetic chains was used. 2. Preganglionic fibres of the pathways producing contraction of the coeliac artery after nerve stimulation seem to leave the central nervous system via the rami communicantes from spinal nerves 1 (and/or 2)-6. The main outflow seems to be via the rami communicantes of the spinal nerve 3. 3. The contraction of the coeliac artery produced by electrical stimulation of the splanchnic nerve, was unaffected by the cholinergic blocking agent atropine (10 −6−10 −5 M), but could be abolished with the alpha adrenergic blocking agent phentolamine (10 −6−10 −5 M), which indicates an effect of stimulation via alpha adrenoceptors. 4. A weak relaxation appeared at each electrical stimulation after blockade of the contraction. The relaxation was probably mediated via beta adrenoceptors, since it was blocked by the beta adrenergic blocking agents propranolol (10 −6 M) or sotalol (10 −6 M), but was unaffected by atropine (10 −6−10 −5 M). 5. No indications of a functioning cholinergic postganglionic innervation was obtained. 6. The response to electrical stimulation of the inflow to the coeliac ganglion could, in contrast to the response to stimulation of the splanchnic nerve, be blocked by the ganglionic blocking agents hexamethonium (10 −5−10 −4 M) or mecamylamine (10 −6−10 −5 M). It is concluded that the cell bodies of the postganglionic neurones to the coeliac artery are mainly located in the coeliac ganglion. 7. Fluorescent histochemistry showed a concentration of the adrenergic innervation in the border between the adventitia and the media of the coeliac artery; no fibres appeared to enter the media.

The Effect of a Ganglion-blocking Agent (Hexamethonium Bromide) upon the Secretory Response to Feeding in Dogs with Selective Vagotomy of the Parietal Cell Mass

Amdrup, B. M. & Griffith, C. A. 1970. The Effect of a Ganglion-blocking Agent (Hexamethonium Bromide) upon the Secretory Response to Feeding in Dogs with Selective Vagotomy of the Parietal Cell Mas...

Uterine response to adrenergic nerve stimulation in the guinea pig.

The effects of hypogastric nerve stimulation on the uterus in the anesthetized guinea pig in estrus are described. Electrical stimulation at frequencies between 1 and 30 pulses per second (pps) with an intensity of 1.5 mA and pulse duration of 1.5 msec for periods up to 5 mm causes either an initiation of or an increase in uterine motility. These effects of nerve stimulation are prevented by an alpha adrenoceptor blocking agent (phentolamine S X 106 g/kg iv). Uterine responses to nerve stimulation at frequencies above 15 pps were not maintained, probably because of the accompanying vascular changes in the uterus. Stimulation of the hypogastric nerves at frequencies between 1 and 6 pps and a lower intensity (1.0 mA) does not elicit uterine contractions per se, but instead increases uterine sensitivity to oxytocin. This increase in sensitivity is slight during stimulation at 1 pps, but becomes highly significant (p < .001) during stimulation at 4 and 6 pps. These results provide indirect evidence that adrenergic nerve impulses can modulate the sensitivity of the myometrial cells to oxytocin. The increase in uterine sensitivity to oxytocin during hypogastric nerve stimulation at 4 pps (1.0 mA) is abolished by an alpha adrenoceptor blocking agent (phentolamine 5 x 10-6 g/kg iv) and potentiated by a beta adrenoceptor blocking aeent (propranolol 5 x log/kg iv). Therefore, the increase in sensitivity is mediated t,j interaction of the neurotransmitter norepinephrine with alpha (stimulatory) adrenoceptor sites in the myometrium. The ganglion-blocking agent hexamethonium (5 mg/kg iv) prevents the increase in uterine sensitivity to oxytocin during hypogastric nerve stimulation. These results show that the increase in sensitivity is mediated by stimulation of preganglionic fibers in the hypogastric nerves. One physiological function of adrenergic nerve activity in the myometrium might be a modulation of myometrial excitability to oxytocin and possibly to other agents as well.

A method for the computation of aortic distensibility in the living human patient and its use for the determination of the aortic effects of aging, drugs, and exercise

Detailed equations are given for the computation of aortic distensibility in the intact living human patient from measurements of systolic and diastolic arterial pressures, heart rate and cardiac output. From these equations, the aortic characteristics of a large series of normal men of different ages were computed. Comparing these results with measurements on excised aortas, a more pronounced trend toward increasing aortic stiffness with increasing age is evident in living than in dead aortas. Nor-epinephrine and exercise apparently cause the living aortas to constrict but to become more distensible. The same change occurs after 30 minutes of high spinal anesthesia. The ganglionic blocking agents hexamethonium, pentamethonium, and tetraethylammonium usually cause the living aorta to become stiffer, presumably due to dilatation. The aortas of patients with pulmonary disease usually react in different fashion to exercise or tetraethylammonium. The increased aortic distensibility that occurs with the hypertension induced by nor-epinephrine or exercise acts as a compensatory mechanism by decreasing systolic pressure.

Role of the sympathetic nervous system in the control of chemical regulation of heat production.

The ganglionic blocking agent hexamethonium chloride and the adrenolytic agent piperoxane hydrochloride prevented the increase in oxygen consumption otherwise observed in curarized, cold-adapted rats exposed to cold. Atropine sulfate had no effect. The sympathetic nervous system, including the adrenal medulla, appears to be important in the mediation of chemical regulation of heat production in these animals. L-noradrenaline was more effective than adrenaline in preventing the fall in oxygen consumption caused by hexamethonium. This finding suggests that noradrenaline may also play an important part in chemical regulation.

Cerebral hemodynamics during controlled hypotension induced by the continuous infusion of ganglionic blocking agents (hexamethonium, pendiomide and arfonad).

Cerebral hemodynamics during controlled hypotension induced by the continuous infusion of ganglionic blocking agents (hexamethonium, pendiomide and arfonad).

A New Type of Autonomic Blocking Agent

THE useful autonomic ganglionic blocking agent hexamethonium, and some of its closely related derivatives, possess quaternary ammonium nitrogen atoms. The activity of the compounds of this type has commonly been associated with the quaternary ammonium salt structure. Certain side-effects of drugs of this type may also be attributed to their quaternary salt nature. In exploring a series of compounds related to W.R.L. No. 51–143, 1-methyl-3-(δ-dimethylaminobutyl)piperidine dihydrochloride, it was discovered that powerful ganglionic blocking activity is also possessed by tertiary amines. The importance of this discovery lies in the facts that not only are these tertiary amines at least as potent and much less toxic than hexamethonium derivatives, but also, lacking the quaternary salt groups of the latter compounds, they should be free of many of the aforementioned side-effects.