The Influence of Propranolol Pretreatment on Acute Tolerance to Norepinephrine Effects on the Systemic and Pulmonary Circulations in Dogs

Turnheim, Klaus; W, Stühlinger

doi:10.1159/000136140

Cited by 2 publications

(4 citation statements)

References 4 publications

(4 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is in contrast to the effects of infused norepinephrine which exhibited a similar vasoconstrictive action, but this effect declined despite continuing infusion after the peak response had been reached (= acute tolerance). This difference confirms a theory proposed earlier [23] that acute norepinephrine tolerance is due to an interaction of the /^-adrenergic with the vasoconstrictive effects of this catechol amine.(2) The pulmonary circulatory effects of methoxamine differ essentially from its peripheral hemodynamic action. There was a decrease in pulmonary perfusion pressure due to a decrease in cardiac output, and the pulmonary vascular resistance fell slightly and insignificantly.…”

supporting

confidence: 87%

“…The development of acute tolerance was abolished by pretreatment with 2 mg/kg propranolol i.v. [23]. This obser vation lead to the conclusion that acute norepinephrine tolerance was due to /^-adrenergic inhibition of the vasoconstrictive catecholamine effect.…”

Section: Results and Comments Acute Tolerance And Methoxaminementioning

confidence: 94%

“…For the comparison of any decline in pressor response during the continuous administration of norepinephrine and methoxamine it was necessary to choose a dose of methoxamine which elevates the systemic blood pressure by approximately the same extent as 0.75 »g/kg/min nor epinephrine in the previous experiments [23]. 25 «g/kg/min methoxamine were found to have this effect and were therefore used in the present study.…”

Section: Results and Comments Acute Tolerance And Methoxaminementioning

confidence: 99%

“…In a previous paper [23] it was proposed that the phenomenon of acute tolerance to circulatory norepinephrine effects is caused by an inter ference of /3-adrenergic metabolic actions with the a-mimetic vasocon strictive effect of this catecholamine. If this hypothesis were true, no tachy phylaxis should be apparent in the effects of a sympathomimetic agent devoid of intrinsic //-adrenergic properties.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The Effects of Methoxamine on the Pulmonary and Systemic Circulations in Comparison to Those of Other Sympathomimetic Agents

Turnheim¹

1971

Pharmacology

Self Cite

View full text Add to dashboard Cite

The effects of i.v. infusions (duration: 15 min) of 25 µg/kg/min methoxamine hydrochloride, an exclusively α-adrenergic sympathomimetic agent, on blood pressure, tolerance blood flow, and vascular resistance in the pulmonary, systemic and femoral circulations were investigated in anesthetized (glucochloralose-N₂O) open chest dogs with artificial respiration. (1) Methoxamine caused a steady and continuous increase in systemic blood pressure, total peripheral- and femoral resistance and a continuous decrease in femoral blood flow throughout the entire duration of the infusion. This is in contrast to the effects of infused norepinephrine which exhibited a similar vasoconstrictive action, but this effect declined despite continuing infusion after the peak response had been reached (= acute tolerance). This difference confirms a theory proposed earlier [23] that acute norepinephrine tolerance is due to an interaction of the β-adrenergic with the vasoconstrictive effects of this catechol-amine. (2) The pulmonary circulatory effects of methoxamine differ essentially from its peripheral hemodynamic action. There was a decrease in pulmonary perfusion pressure due to a decrease in cardiac output, and the pulmonary vascular resistance fell slightly and insignificantly. In contrast, the systemic blood pressure and the total peripheral resistance were markedly increased. It is concluded that the reactivity of the pulmonary blood vessels to the vasoconstrictive property of methoxamine is much smaller than that of the systemic vasculature. (3) In a comparison of the pulmonary circulatory effects of 10 sympathomimetic agents with different ratios of α- to β-adrenergic properties it is pointed out that strong β-receptor stimulants increase the pulmonary perfusion pressure, whilst potent α-receptor stimulants lower it or do not change it. The pulmonary vascular resistance is increased most with those sympathomimetics which seem to possess approximately equally strong α- and β-mimetic properties, whilst during the administration of predominantly α- or β-adrenergic agents only very small changes in pulmonary vascular resistance were observed.

show abstract

supporting

confidence: 87%

Section: Results and Comments Acute Tolerance And Methoxaminementioning

confidence: 94%

Section: Results and Comments Acute Tolerance And Methoxaminementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations