Summary
The effects of intrathecal, intracisternal and intravenous injections of yohimbine (10 μg) on hypotensive and bradycardic responses to the alpha agonist guanabenz (10 μg/kg, i.v.) were studied in anesthetized rats. The depressor response to guanabenz was inhibited by intrathecal pretreatment with yohimbine, while this pretreatment did not affect the bradycardic response to guanabenz. Intracisternal pretreatment with yohimbine inhibited both cardiovascular responses to guanabenz, whereas intravenous pretreatment with yohimbine affected neither. Guanabenz (1 μg) decreased blood pressure when injected intrathecally but did not affect it when injected intravenously. These results suggest that in rats spinal alpha adrenoceptors are involved in mediation of the hypotensive action of the alpha agonist guanabenz injected systemically.
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References
Connor HE, Drew GM, Finch L, Hicks PE (1981) Pharmacological characteristics of spinal α-adrenoceptors in rats. J Auton Pharmacol 1:149–156
Coote JH, Macleod VH (1972) The possibility that noradrenaline is a sympatho-inhibitory transmitter in the spinal cord. J Physiol (Lond) 225:44P-46P
Hukuhara T Jr, Otsuka Y, Takeda R, Sakai F (1968) Die zentralen Wirkungen des 2-(2,6-Dichlorophenylamino)-2-Imidazolinhydrochlorids. Arzneim Forsch 18:1147–1153
Kobinger W (1978) Central α-adrenergic systems as targets for hypotensive drugs. Rev Physiol Biochem Pharmacol 81:39–100
Kobinger W, Pichler L (1975) Localization in the CNS of adrenoceptors which facilitate a cardioinhibitory reflex. Naunyn-Schmiedeberg's Arch Pharmacol 286:371–377
Kobinger W, Pichler L (1980) Relation between central sympathoinhibitory and peripheral pre- and postsynaptic α-adrenoceptors as evaluated by different clonidine-like substances in rats. Naunyn-Schmiedeberg's Arch Pharmacol 315:21–27
Kubo T (1978) Cardiovascular reactivity in renal and spontaneously hypertensive rats. Arch Int Pharmacodyn Ther 234:49–57
Kubo T, Nagura J, Misu Y (1987) Pharmacological characterization of spinal alpha adrenoceptors related to blood pressure control in rats. J Pharmacol Exp Ther 240:298–302
Lim HC, Chan SHH (1986) The roles of α2-adrenoceptors in the nucleus reticularis gigantocellularis and vagal mechanism in the cardiovascular suppressive effects of guanabenz in the rat. Neurosci Lett 63:45–50
Neumayr RJ, Hare BD, Franz DN (1974) Evidence for bulbospinal control of sympathetic preganglionic neurons by monoaminergic pathways. Life Sci 14:793–806
Schmitt H (1977) The pharmacology of clonidine and related products. In: Gross F (ed) Antihypertensive agents. Springer, Berlin Heidelberg New York, pp 299–396
Schmitt H, Schmitt H (1969) Localization of the hypotensive effect of 2-(2,6-dichlorophenylamino)-2-imidazoline hydrochloride (St 155, Catapresan). Eur J Pharmacol 6:8–12
Sinha JN, Atkinson JM, Schmitt H (1973) Effects of clonidine and 1-dopa on spontaneous and evoked splanchnic nerve discharge. Eur J Pharmacol 24:113–119
Starke K, Montel H, Gayk W, Merker R (1974) Comparison of the effects of clonidine on pre- and postsynaptic adrenoceptors in the rabbit pulmonary artery. Naunyn-Schmiedeberg's Arch Pharmacol 285:133–150
Yaksh TL, Rudy TA (1976) Chronic characterization of the spinal subarachnoid space. Physiol Behav 17:1031–1036
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Kubo, T., Hata, H. & Misu, Y. Involvement of spinal alpha adrenoceptors in mediation of the hypotensive action of guanabenz in rats. Naunyn-Schmiedeberg's Arch Pharmacol 337, 122–124 (1988). https://doi.org/10.1007/BF00169489
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DOI: https://doi.org/10.1007/BF00169489