scispace - formally typeset
Search or ask a question

Showing papers by "Andreas Pfeiffer published in 1983"


Journal ArticleDOI
TL;DR: Evidence is provided that mu-opiate receptors primarily mediate cardiovascular effects of opiates in awake rats, at low doses, a sympathetic adrenomedullary activation occurs, whereas higher doses additionally activate parasympathetic efferents, both possibly from anterior hypothalamic sites.
Abstract: Intracerebroventricular injections of selective opioid agonists were used to investigate the role of opiate receptor subtypes in cardiovascular function in awake rats. The μ-agonist (D-Ala2,MePhe4,Gly5-ol)enkephalin (1 nmol) caused a prolonged increase in blood pressure and an initial decrease followed by a delayed increase in heart rate. These effects were antagonized by the selective μ-antagonist β-funaltrexamine. A selective 5-agonist (dimeric tetrapeptide enkephalin) was devoid of cardiovascular effects at 10 nmol, whereas a benzomorphan κ-agonist MRZ caused a pressor response which was not antagonized by β-funaltrexamine. The mechanisms by which opioids elicit cardiovascular effects were analyzed in detail by using microinjections into the anterior hypothalamic area. Low doses of enkephalin produced increases in heart rate and blood pressure. Associated elevations of plasma norepinephrine and epinephrine, but not vasopressin, suggested a stimulation of sympatho-adrenomedullary pathways. Higher doses ...

90 citations


Journal ArticleDOI
01 Sep 1983-Peptides
TL;DR: The mu-receptor seems to be the primary opiate receptor involved in the regulation of LH secretion, and none of the opiate agonists employed had an effect on FSH secretion.

69 citations


Journal Article
TL;DR: Findings implicate mu-receptors in mediating the cardiovascular and respiratory effects of opiates at anterior hypothalamic sites in central cardiovascular regulation of the unanesthetized rat.
Abstract: Relatively selective mu-, delta- and kappa-opiate agonists were microinjected into anterior hypothalamic and septal brain regions of the unanesthetized rat in order to investigate the potential role of specific opiate receptors in central cardiovascular regulation. Low doses (0.2-3 nmol) of both [D-Ala2,MePhe4,Gly-(ol)5] enkephalin (DAGO, mu-agonist) and [D-Ala2,D-Leu5]enkephalin (DADL, delta-agonist) caused dose-dependent increases in blood pressure and heart rate which were naloxone reversible. Higher doses (7.5-30 nmol) of DAGO and DADL produced pressor responses but had little effect on heart rate. The kappa-agonist MR 2034 had no effect on cardiovascular parameters at these doses. DAGO but not MR 2034 also depressed respiration at the higher doses resulting in hypoxia, hypercapnia and acidosis while DADL only slightly depressed respiration. DAGO was approximately 10-fold more potent than DADL in eliciting cardiovascular and respiratory responses. These findings implicate mu-receptors in mediating the cardiovascular and respiratory effects of opiates at anterior hypothalamic sites.

62 citations


Journal ArticleDOI
TL;DR: Sheep brain membrane opiate receptors were solubilized using two different approaches: chaps was used to solubILize [3H]buprenorphine labeled membranes and Digitonin-NaCl was used forsolubilization of receptors which were then labeled with [ 3H]diprenorphines.

5 citations