| 1. |
- Koskinen, Lars-Owe D., Professor, 1955-
(författare)
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Naloxone and TRH affect regional blood flows in the anesthetized rabbit.
- 1991
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Ingår i: Peptides. - : Elsevier BV. - 0196-9781 .- 1873-5169. ; 12:6, s. 1273-1277
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Tidskriftsartikel (refereegranskat)abstract
- The cardiovascular effects of IV naloxone and a subsequent administration of TRH IV were studied in the rabbit. Naloxone caused a vasodilation in the myocardium and adrenal glands. Naloxone elicited an increment in cerebral blood flow in several regions which attenuated the cerebrovasodilating effect of TRH in a few regions. The blockade of endogenous opioids with naloxone did not modify the peripheral vasoconstricting effect of TRH or affect the vascular effects of TRH mediated by the peripheral sympathetic nerves. The results indicate that naloxone has a vasodilating effect in the myocardium and CNS in anesthetized rabbits. The major part of the cardiovascular effect of TRH is not dependent on mechanisms sensitive to naloxone.
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| 2. |
- Koskinen, Lars-Owe D., Professor, 1955-
(författare)
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The influence of muscarinic and prostaglandic mechanisms on regional cerebral and peripheral blood flows and on the vascular effects of thyrotropin releasing hormone (TRH).
- 1994
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 152:4, s. 399-406
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Tidskriftsartikel (refereegranskat)abstract
- TRH has pronounced vascular effects. The final transmitter mechanisms of these effects are not fully understood. The present study was conducted in order to elucidate whether these effects are mediated by prostaglandic or muscarinic mechanisms. Muscarinic blockade augmented the vasoconstricting- and pressor effect of TRH; vasodilation in the brain was attenuated only in the caudate nucleus. Indomethacin provoked a decrease in regional cerebral blood flow and in the gastric mucosal blood flow. No effect of indomethacin was observed on the vascular effects of TRH. It is concluded that the cerebral vasodilating and peripheral vasoconstricting effects of TRH are not mediated by prostaglandins. Muscarinic mechanisms are involved in the vasodilating effect of TRH only in the caudate nucleus.
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| 3. |
- Seligsohn, E. E., et al.
(författare)
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Effects of alpha 2-adrenoceptor blockade and thyrotropin-releasing hormone (TRH) on the cardiovascular system in the rabbit.
- 1991
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 143:2, s. 187-194
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Tidskriftsartikel (refereegranskat)abstract
- The effects of two different doses of thyrotropin-releasing hormone on regional blood flows were studied in urethane-anaesthetized rabbits pretreated with the alpha 2-adrenergic antagonists yohimbine and idazoxan. The effects of yohimbine were also studied using unanaesthetized rabbits. Blood flow measurements were performed using the tracer microsphere method. Thyrotropin-releasing hormone was injected i.v. at a dose of either 0.1 mg kg-1 or 2.0 mg kg-1. Yohimbine and idazoxan did not modify the effect of thyrotropin-releasing hormone on mean arterial blood pressure. In the anaesthetized animals, blockade of the alpha 2-adrenoceptors resulted in a vasoconstriction in several peripheral organs and the vasoconstriction increased after thyrotropin-releasing hormone administration. Pretreament with yohimbine reduced total cerebral blood flow moderately and in such animals thyrotropin-releasing hormone elicited only minor cerebral blood flow effects. Pretreatment with idazoxan did not reduce the total cerebral blood flow and in such animals it increased from 53 +/- 1 to 75 +/- 4 g min-1 100 g-1 (P less than 0.01) after the administration of the lower dose of thyrotropin-releasing hormone and from 64 +/- 5 to 112 +/- 17 g min-1 100 g-1 (P less than 0.01) after the higher dose. In the conscious animals, yohimbine caused an increase in mean arterial blood pressure and heart rate. Vascular resistance increased in several organs. The cerebral blood flow decreased in white matter (P less than 0.05) and the caudate nucleus (P less than 0.05). The results indicate that there is a yohimbine-sensitive mechanism involved in the cerebrovasodilating effect of thyrotropin-releasing hormone in anaesthetized rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)
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