Inhibitory Effects of Clonidine and Bs 100‐141 on Responses to Sympathetic Nerve Stimulation in Cats and Rabbits

Pacha, W; Salzmann, R; Scholtysik, G

doi:10.1111/j.1476-5381.1975.tb07388.x

Cited by 43 publications

(15 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…(1975) and can be explained by its agonist action at presynaptic a-adrenoceptors (Langer, 1974). The proposed presynaptic action of clonidine was supported by the finding that phentolamine antagonized the inhibition of sympathetic cardioacceleration (Pacha et al, 1975, Drew, 1976.…”

Section: Discussionsupporting

confidence: 48%

“…The studies of Pacha, Salzmann & Scholtysik (1975) suggested that these presynaptic a-adrenoceptors are not distributed uniformly throughout the peripheral sympathetic nervous system. These workers found that in the spinal cat, cardiapc sympathetic nerves appeared to be more sensitive to a-adrenoceptor-mediated inhibition of impulse transmission than sympathetic nerves supplying the nictitating membrane.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Inhibitory Effects of Clonidine on Responses to Sympathetic Nerve Stimulation in the Pithed Rat

Doxey

Everitt

1977

British J Pharmacology

View full text Add to dashboard Cite

I The spinal sympathetic outflow to the eyelid, heart, splanchnic blood vessels, vas deferens and anococcygeus muscle was stimulated in pithed rats. 2 Clonidine inhibited sympathetic outflow to all of the tissues studied. The inhibitory effects of clonidine on cardiac nerves and hypogastric nerves were antagonized by phentolamine. 3 Clonidine produced a postsynaptic a-adrenoceptor agonist action on the eyelid, splanchnic blood vessels and the anococcygeus muscle. These effects were also antagonized by phentolamine. 4 The effects of clonidine, naphazoline and oxymetazoline on pre-and postsynaptic a-adrenoceptors were determined. 5 The presynaptic a-adrenoceptors employed were situated in either the sympathetic cardiac or hypogastric nerve terminals. Increases in diastolic blood pressure were used to assess concurrent postsynaptic a-adrenoceptor agonist activity. 6 The presynaptic a-adrenoceptor agonist potencies of clonidine, naphazoline and oxymetazoline were very similar on cardiac nerve terminals whereas on the hypogastric nerve terminals oxymetazoline was about 6 times more potent than either naphazoline or clonidine. 7 The results support the view that presynaptic a-adrenoceptors regulate transmitter release in sympathetic nerves. There appear to be subtle differences between the presynaptic a-adrenoceptors of different sympathetic nerve endings.

show abstract

Section: Discussionsupporting

confidence: 48%

Section: Introductionmentioning

confidence: 99%

Inhibitory Effects of Clonidine on Responses to Sympathetic Nerve Stimulation in the Pithed Rat

Doxey

Everitt

1977

British J Pharmacology

View full text Add to dashboard Cite

show abstract

“…Reduction of the bradycardia to clonidine is, however, partly due to an antagonism of the presynaptic inhibition of the drug on the cardiac sympathetic nerve terminals by an a-adrenoceptor blocking agent (20,21). Reserpine shows a significant potentiation of the bradycardia to clonidine in conscious rats and this potentiation is con sidered to be caused by summation of the activities of the baroceptor-vagal reflex with a combination of clonidine and reserpinc, since it is well known that reserpine itself causes a vagal stimulation as a result of the increase in the central parasympathetic activity (22)(23)(24)(25).…”

Section: Discussionmentioning

confidence: 99%

Effect of Clonidine on Blood Pressure, Heart Rate and Body Temperature in Conscious Rats

Ozawa

Chen

Watanabe

et al. 1977

Japanese Journal of Pharmacology

View full text Add to dashboard Cite

Abstract-Effects of clonidine on blood pressure, heart rate and rectal temperature in conscious rats were examined. Clonidine (0.1-1 mg/kg s.c.) caused a prevailing pressor response and dose-dependently a fall in heart rate and body temperature.The pressor response to clonidine (0.3 mg/kg s.c.) was completely reduced by phentolamine (10 mg/kg s.c.), chlorpromazine (10 mg/kg s.c.) but not by hexamethonium (30 mg/kg i.p.), guanethidine (30 mg/kg s.c.) or reserpine (5 mg/kg s.c. 18 hr+ 1 mg/kg i.p. 4 hr prior to clonidine). Conversely, a remarkable potentiation of the pressor response to clonidine was observed after treatment with reserpine. The bradycardia with clonidine (0.3 mg/kg s.c.) was significantly reduced by phentolamine, chlorpromazine or atropine (5 mg/kg s.c.) but was potentiated by reserpine. The hypothermia with clonidine (0.3 mg/kg s.c.) was not influenced by phentolamine or atropine but was significantly potentiated by chlorpromazine.From the above results it is suggested that the pre vailing pressor response to clonidine in conscious rats is due to a stimulation of peri pheral a-adrenoceptors, the bradycardia with clonidine is exerted through the sympa thetic pathway and the baroceptor-vagal reflex, and that the hypothermia with clonidine is mainly due to the central mechanism.

show abstract

“…The response to very low intramuscular doses of guanfacin compared to a lack of response to intracerebral administration has been suggested as evidence of peripheral thermogenic mediation in cattle (Hunter et al 1993). Although skeletal muscle does not contain α 2 receptors, it is known that α 2 receptors on sympathetic nerves will reduce noradrenalin release (Pacha et al 1975), which may result in reduced heat production in muscle and other tissues. Consistent with this suggestion is the observation that large variations in sheep hindquarter thermogenic responses to adrenaline or cold exposure (Ole Miaron and Christopherson 1996) accompany the whole body thermogenic responses.…”

Section: Resultsmentioning

confidence: 99%

Thermogenic and digestive responses of ad libitum fed pigs to α₂-adrenergic stimulation with guanfacin in different thermal environments

Cosgrove¹,

Mosenthin²,

Christopherson³

et al. 2002

Can. J. Anim. Sci.

View full text Add to dashboard Cite

2002. Thermogenic and digestive responses of ad libi-tum fed pigs to α α 2-adrenergic stimulation with guanfacin in different thermal environments. Can. J. Anim. Sci. 82: 79-86. Guanfacin, an α 2-adrenoceptor agonist, reduces heat production in cold-stressed, but not heat-stressed animals. Growth rate, feed intake, metabolic rate, ileal and fecal digestibility were measured in 16 pigs, housed in neutral (20.4 ± 1.7°C), hot (32.7 ± 1.6°C) or cold (6.6 ± 1.4°C) environments. For ileal digestibility determination, pigs received 80 mg kg-1 d-1 followed by 3 × 40 mg kg-1 d-1 of guanfacin or saline, within their own environment, in a cross-over design. Fecal digestibility and heat production were measured over 7 d with treatments applied in a cross-over design of two periods. Oxygen consumption (VO 2) was determined by open circuit respiration calorime-try. Cold-housed pigs had higher feed intakes (P < 0.05), but not growth rates, compared with those in the thermoneutral environment. Pigs in the hot environment had lower feed intakes, weight gains and heat production (P < 0.05) and higher rectal temperatures (P < 0.05) compared to those in the other two environments. Guanfacin did not reduce heat production in swine in any environment. Pigs in the cold and neutral environments had lower (P < 0.05) fecal dry matter (DM) digestibility. Pigs in the cold had lower fecal gross energy (GE) digestibility (P < 0.05) compared to those in the hot, and lower fecal crude protein (CP) digestibility (P < 0.05) compared to those in the neutral or hot environments, probably due to changes in digesta retention in the large intestine. Temperature did not affect ileal digestibil-ity of DM, GE, CP and amino acids. Guanfacin did not affect fecal digestibility, but increased ileal DM and GE digestibility (P < 0.05) across all temperatures, possibly by affecting smooth muscle contraction and rate of passage. Increased ileal energy digestibility without a change in heat production suggests an improvement in utilization of DE in response to guanfacin. Key words: α 2-adrenoceptor agonist, digestibility, pig, environment, heat production, ileum Cosgrove, S. J., Mosenthin, R., Christopherson, R. J., Li, B. T. et Sauer W. C. 2002. Réaction thermogénique et digestive des porcs nourris à satiété à la stimulation α α 2-adrénergique par la guanfacine à divers régimes thermiques. Can. J. Anim. Sci. 82: 79-86. La guanfacine, agoniste des récepteurs α 2-adrénergiques, diminue la production de chaleur chez les animaux qui subissent un stress dû au froid, mais pas chez ceux soumis à un stress thermique. Les auteurs ont déterminé le taux de croissance, la prise alimentaire, le taux métabolique et la digestibilité iléale et fécale chez seize porcs logés à une température neutre (20,4 ± 1,7°C), élevée (32,7 ± 1,6°C) ou basse (6,6 ± 1,4°C). Pour mesurer la digestibilité iléale, on a donné aux animaux 80 mg kg-1 puis 3 × 40 mg kg-1 de guanfacine ou de saline par jour dans leur environnement, selon un plan croisé. La digestibilité fécale et la production de cha...

show abstract

Inhibitory Effects of Clonidine and Bs 100‐141 on Responses to Sympathetic Nerve Stimulation in Cats and Rabbits

Cited by 43 publications

References 8 publications

Inhibitory Effects of Clonidine on Responses to Sympathetic Nerve Stimulation in the Pithed Rat

Inhibitory Effects of Clonidine on Responses to Sympathetic Nerve Stimulation in the Pithed Rat

Effect of Clonidine on Blood Pressure, Heart Rate and Body Temperature in Conscious Rats

Thermogenic and digestive responses of ad libitum fed pigs to α₂-adrenergic stimulation with guanfacin in different thermal environments

Contact Info

Product

Resources

About

Inhibitory Effects of Clonidine and Bs 100‐141 on Responses to Sympathetic Nerve Stimulation in Cats and Rabbits

Cited by 43 publications

References 8 publications

Inhibitory Effects of Clonidine on Responses to Sympathetic Nerve Stimulation in the Pithed Rat

Inhibitory Effects of Clonidine on Responses to Sympathetic Nerve Stimulation in the Pithed Rat

Effect of Clonidine on Blood Pressure, Heart Rate and Body Temperature in Conscious Rats

Thermogenic and digestive responses of ad libitum fed pigs to α2-adrenergic stimulation with guanfacin in different thermal environments

Contact Info

Product

Resources

About

Thermogenic and digestive responses of ad libitum fed pigs to α₂-adrenergic stimulation with guanfacin in different thermal environments