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Biomedical subjects

L Edvinsson

Publications and source records attributed to L Edvinsson.

At least 55 records · Page 3Linked to original sources

Neuropeptide localization in the "migraine generator" region of the human brainstem.

Evidence from animals and humans suggests that brainstem nuclei such as the raphe nuclei, the locus coeruleus (LC) and the periaqueductal grey matter (PAG), are involved in the pathophysiology of migraine. In order to understand possible neurotransmitters involved we have, by means of indirect immunocytochemistry, analysed these regions for the occurrence and distribution of calcitonin gene-related peptide (CGRP), substance P (SP), pituitary adenylate-cyclase activating peptide (PACAP) and vasoactive intestinal polypeptide (VIP). CGRP-immunoreactive (-ir) cell bodies, but no fibres, were found to occur in high numbers, constituting 80% of all nerve cell bodies in the LC. A smaller number of these nerve cell bodies (40%) in the LC proved to be PACAP-ir. The LC neurones also stored the vesicular monoamine transporter (VMAT)- and the C-terminal flanking peptide of neuropeptide Y (C-PON)-ir, illustrating their adrenergic nature. Double immunostaining revealed that all VMAT-and C-PON-containing neurones, in addition, stored CGRP. Immunoreactive cell bodies were not seen in the nucleus raphe magnus (NRM) or PAG. Numerous SP-ir nerve fibres were observed in the NRM, the LC and the PAG. Few PACAP-ir nerve fibres were detected in the PAG and few VIP-ir nerve fibres were seen in the NRM and the PAG.

Adult↗

Expression of 5-HT1B receptors in human nasal mucosa.

5-HT1B receptors were discovered in human nasal mucosa using immunocytochemistry. Strong immunoreaction was seen around small blood vessels mainly confined to the smooth muscle cell layer. In contrast, no immunoreaction for 5-HT1D was seen. The possibility of local release in connection with specific target receptors suggests a role for 5-HT in the regulation of vascular tone, glandular secretion and epithelial functions and that 5-HT1B receptor agonists may be of clinical importance.

Adult↗

Neuropeptide Y-mediated constriction and dilation in rat middle cerebral arteries.

Neuropeptide Y (NPY) is an important vasoconstrictor in the cerebral circulation. Its constrictor response is because of activation of NPY receptors on the vascular smooth muscle (VSM). Little is known regarding the effects of NPY on the endothelium. In the current study, the authors tested the hypothesis that NPY can either constrict or dilate rat middle cerebral arteries (MCAs). Constriction is elicited by stimulating receptors on the VSM; dilation is elicited by stimulating receptors on the endothelium. Middle cerebral arteries were isolated, cannulated with micropipettes, pressurized to 85 mm Hg, and luminally perfused. The extraluminal application of NPY (mixed agonist), [Leu31, Pro34]-NPY (Y1 agonist), or NPY-[13-36] (Y2 agonist) produced concentration-dependent constrictions. BIBP 3226 (Y1 selective antagonist) significantly attenuated the NPY- and [Leu31, Pro34]-NPY-induced constrictions. The luminal application of NPY, [Leu31, Pro34]-NPY, and NPY-[13-36] produced concentration-dependent dilations of MCAs. The maximum dilation produced by the NPY receptor agonists was approximately 40% of the dilation elicited by the luminal administration of 10(-5) mol/L ATP. Dilations elicited by luminal NPY, [Leu31, Pro34]-NPY, or NPY-[13-36] were abolished by inhibition of nitric oxide synthase with 10(-5) mol/L Nomega-nitro-L-arginine methyl ester (L-NAME) or removal of the endothelium. Dilations produced by luminal NPY or luminal [Leu31, Pro34]-NPY were not affected by BIBP 3226. Stimulation of NPY receptors on vascular smooth muscle constricted MCAs. Stimulation of an NPY receptor other than the Y1 subtype on endothelium dilated the MCAs by releasing nitric oxide.

Animals↗

Sensory nerves in man and their role in primary headaches.

The sensory innervation of intracranial vessels originate in the trigeminal ganglion and comprise the following signal substances; calcitonin gene-related peptide (CGRP), substance P, neurokinin A, pituitary adenylate cyclase activating peptide (PACAP) and nitric oxide (NO). Studies in patients have revealed a clear association between head pain and the release of CGRP. In cluster headache and in a case of chronic paroxysmal headache there is in addition release of vasoactive intestinal peptide (VIP), which was associated with the facial symptoms (nasal congestion, rhinorrhea). In parallel with triptan administration, acting via 5-HT(1B/1D) receptors, head pain subside and neuropeptide release normalise. These data show the involvement of sensory and parasympathetic mechanisms in the pathophysiology of primary headaches.

Animals↗

Calcitonin gene-related peptide (CGRP) and the pathophysiology of headache: therapeutic implications.

Cerebral blood vessels are innervated by sensory nerves that store several neurotransmitters. In primary headaches, there is a clear association between head pain and the release of the neuropeptide calcitonin gene-related peptide (CGRP). Furthermore, when triptan antimigraine agents are administered, headache subsides and the neuropeptide release normalises, in part via a presynaptic effect. The central role of CGRP in primary headaches has led to the search for suitable antagonists of the receptors for this neuropeptide, which it is hoped will have less cardiovascular adverse effects than the triptans. Recently, the initial pharmacological profile of such a group of compounds has been disclosed. These compounds are small molecules with high selectivity for human CGRP receptors. Hypothetically, these agents will be efficacious in the relief of migraine headaches via blockade of the effects of CGRP.

Animals↗

CGRP and adrenomedullin receptor populations in human cerebral arteries: in vitro pharmacological and molecular investigations in different artery sizes.

The aim of the present study was to determine functional and molecular characteristics of receptors for calcitonin gene-related peptide (CGRP) and adrenomedullin in three different diameter groups of lenticulostriate arteries. Furthermore, the presence of perivascular neuronal sources of CGRP was evaluated in these arteries. In the functional studies, in vitro pharmacological experiments demonstrated that both CGRP and adrenomedullin induce alpha-CGRP-(8-37) sensitive vasodilation in artery segments of various diameters. The maximal amounts of vasodilation induced by CGRP and adrenomedullin were not different, whereas the potency of CGRP exceeded that of adrenomedullin by 2 orders of magnitude. Significant negative correlations between artery diameters and maximal responses were demonstrated for CGRP and adrenomedullin. In addition, the potency of both peptides tended to increase in decreasing artery diameter. In the molecular experiments, levels of mRNAs encoding CGRP receptors and receptor subunits were compared using reverse transcriptase polymerase chain reactions (RT-PCR). The larger the artery, the more mRNA encoding receptor activity-modifying proteins 1 and 2 (RAMP1 and RAMP2) was detected relative to the amount of mRNA encoding the calcitonin receptor-like receptor. By immunohistochemistry, perivascular CGRP containing nerve fibres were demonstrated in all the investigated artery sizes. In conclusion, both CGRP and adrenomedullin induced vasodilation via CGRP receptors in human lenticulostriate artery of various diameter. The artery responsiveness to the CGRP receptor agonists increased with smaller artery diameter, whereas the receptor-phenotype determining mRNA ratios tended to decrease. No evidence for CGRP and adrenomedullin receptor heterogeneity was present in lenticulostriate arteries of different diameters.

Adrenomedullin↗

Positive inotropy mediated via CGRP receptors in isolated human myocardial trabeculae.

Isometric contractile force were studied on isolated human myocardial trabeculae that were paced at 1.0 Hz in tissue baths. Alpha calcitonin gene-related peptide (alpha-CGRP) had a potent positive inotropic effect in most trabeculae from both the right atrium and left ventricle, and this effect was partially antagonized by the CGRP(1) receptor antagonist alpha-CGRP-(8-37) (10(-6) M). Amylin and the CGRP(2) receptor agonist [Cys(acetylmethoxy)(2, 7)]CGRP had a positive inotropic effect in some trabeculae, whereas adrenomedullin had no inotropic effect. Using reverse transcriptase-polymerase chain reaction (PCR) mRNAs encoding the human calcitonin receptor-like receptor and the receptor associated modifying proteins (RAMPs) RAMP1, RAMP2, and RAMP3 were detected in human myocardial trabeculae from both the right atrium and left ventricle. In conclusion, functional CGRP(1) and CGRP(2) receptors may mediate a positive inotropic effect at both the atrial and ventricular level of the human heart. mRNAs for calcitonin receptor-like receptor and specific RAMPs further support the presence of CGRP receptors.

Adrenomedullin↗

Increased sensitivity to ET-1 in rat cerebral arteries following organ culture.

Endothelin-1 (ET-1) is recognized as being involved in the pathophysiology of cerebrovascular diseases. Using organ culture as a model for possible pathological changes we studied changes in ET(A) and ETB receptor function using a sensitive in vitro method. We observed an up-regulation of the ET(B) receptor and an amazingly increased sensitivity to ET-1 by 3 log units in pEC50; pEC50(fresh) was 8.7 +/- 0.1, and pEC50(cultured) was 11.7 +/- 0.3. pA2 for FR139317 in the fresh vessel was 7.0 +/- 0.2 whereas it could not be obtained for the cultured vessel, indicating a possible cross-talk between the ET(A) and ET(B) receptors. The increased sensitivity to ET-1 could also take place during cerebrovascular disease such as stroke or haemorrhage rendering the vessels considerably more sensitive to ET-1.

Animals↗

P2X receptors counteract the vasodilatory effects of endothelium derived hyperpolarising factor.

Dilatory responses of extracellular nucleotides were examined in the precontracted isolated rat mesenteric artery. Dilatation mediated by endothelium-derived hyperpolarising factor (EDHF) was studied in the presence of Nomega-nitro-L-arginine (L-NOARG) and indomethacin, and was most potently induced by the selective P2Y(1) receptor agonist adenosine 5'-O-thiodiphosphate (ADPbetaS), while 2-methylthioadenosine triphosphate (2-MeSATP) and adenosine triphosphate (ATP) were almost inactive. However, after P2X receptor desensitisation (with alphabeta-methylene-adenosine triphosphate, alphabeta-MeATP), 2-MeSATP and ATP potently stimulated EDHF-mediated dilatation. This can be explained by simultaneous activation of endothelial P2Y receptors that release EDHF, and depolarising P2X receptors on smooth muscle cells. Uridine triphosphate (UTP) also induced potent dilatation, suggesting EDHF release via P2Y(2)/P2Y(4) receptors. Uridine diphosphate (UDP) had only minor dilatory effects, and when pretreated with hexokinase it was almost inactive, suggesting a minor role for P2Y(6) receptors. The nitric oxide (NO) mediated dilatation was studied in the presence of charybdotoxin, apamin and indomethacin. ADPbetaS, 2-MeSATP, ATP and UTP were all potent relaxant agonists suggesting NO release via P2Y(1) and P2Y(2)/P2Y(4) receptors, while UDP was much less potent and efficacious. P2X receptor desensitisation had only minor effect on the NO-mediated dilatations. In conclusion, both EDHF and NO-mediated dilatation can be induced by activation of P2Y(1) and P2Y(2)/P2Y(4) receptors. P2X receptor stimulation of smooth muscle cells selectively counteracts the dilatory effect of EDHF.

Animals↗

Influence of ageing on vasomotor responses of human epicardial coronary arteries.

Vasomotor responses to various agonists were studied on isolated circular segments of human epicardial coronary arteries from three different age groups; 23-38 years, 40-58 years and 63-86 years. Noradrenaline had no or only weak contractile effect on coronary arteries from younger patients but induced contraction of all artery segments from older patients. The Emax value was significantly (P<0.0001) higher in arteries from the oldest group compared to each of the two younger age groups, whereas the potency was similar in all three groups. Linear regression analysis of noradrenaline-induced contraction in individual patients revealed a significantly positive age-correlation (correlation coefficient 0.67, P<0.0001). Contraction induced by endothelin-1 and relaxation induced by substance P, calcitonin gene-related peptide and vasoactive intestinal peptide on arteries precontracted with U46619 showed no significant differences in maximum responses and potencies between the three age groups, and no significant linear age-correlation. These data demonstrate a large variability in contractile responses to noradrenaline with contractions seen mostly in coronary arteries from older patients. It thus seems that sympathetic activation could contribute to coronary ischaemia in some patients.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

Modulation of contractile force by endothelin receptors in porcine myocardial trabeculae.

The aim of the study was to determine possible inotropic effects mediated by endothelin-A and endothelin-B receptors in porcine myocardial trabeculae from right atria and left ventricles. Isolated trabeculae were paced at 1.5 Hz in tissue baths, and changes in isometric contractile force upon exposure to agonist were studied. Endothelin-1 and endothelin-3 had a strong and potent positive inotropic effect in all trabeculae. In all atrial and in some ventricular trabeculae this effect was preceded by a transient negative inotropic effect at 10(-7) M. The endothelin-B receptor agonist IRL 1620 had a positive inotropic effect in some of the ventricular trabeculae, and no negative inotropic effect. Another endothelin-B receptor agonist, sarafotoxin S6c, had no positive inotropic effect, but induced a transient negative inotropic effect in some atrial trabeculae at 10(-7) M. In atrial trabeculae the preincubation with the endothelin-A receptor antagonist FR139317 (10(-6) M) decreased significantly (P<0.01) the maximum positive inotropic responses and abolished negative inotropic responses to endothelin-1. In conclusion, both endothelin-A and endothelin-B receptors may have the potential to mediate both positive and negative inotropic responses, but a positive inotropic effect mediated mainly via endothelin-A receptors seems to predominate.

Analysis of Variance↗

The stable pyrimidines UDPbetaS and UTPgammaS discriminate between the P2 receptors that mediate vascular contraction and relaxation of the rat mesenteric artery.

The contractile and relaxant effects of the different P2 receptors were characterized in the rat isolated mesenteric artery by use of extracellular nucleotides, including the stable pyrimidines uridine 5'-O-thiodiphosphate (UDPbetaS) and uridine 5'-O-3-thiotriphosphate (UTPgammaS). The selective P2X receptor agonist, alphabeta-methylene-adenosine triphosphate (alphabeta-MeATP) stimulated a potent (pEC(50)=6.0) but relatively weak contraction (E:(max)=57% of 60 mM K(+)). The contractile concentration-response curve of adenosine triphosphate (ATP) was biphasic when added in single concentrations. The first part of the response could be desensitized by alphabeta-MeATP, indicating involvement of P2X receptors, while the second part might be mediated by P2Y receptors. The contractile P2Y receptors were further characterized after P2X receptor desensitization with 10 microM alphabeta-MeATP. Uridine diphosphate (UDP), uridine triphosphate (UTP) and ATP stimulated contraction only in high concentrations (1 - 10 mM). The selective P2Y(6) agonist, UDPbetaS, and the P2Y(2)/P2Y(4)-receptor agonists UTPgammaS and adenosine 5'-O-3-thiotriphosphate (ATPgammaS) were considerably more potent and efficacious (E:(max) approximately 250% of 60 mM K(+)). Adenosine 5'-O-thiodiphosphate (ADPbetaS) was inactive, excluding contractile P2Y(1) receptors. After precontraction with 1 microM noradrenaline, UTP, ADP and ATP induced relaxations with similar potencies (pEC(50) approximately 5.0). UTPgammaS, ADPbetaS and ATPgammaS were approximately one log unit more potent indicating the presence of endothelial P2Y(1) and P2Y(2)/P2Y(4) receptors. The P2Y(6) receptor agonist, UDPbetaS, had no effect. UDPbetaS and UTPgammaS are useful tools when studying P2 receptors in tissue preparations with ectonucleotidase activity. Contractile responses can be elicited by stimulation of P2Y(6) and, slightly less potently, P2Y(2)/P2Y(4) receptors. The P2X response was relatively weak, and there was no P2Y(1) response. Stimulation of P2Y(1) and P2Y(2)/P2Y(4) receptors elicited relaxation, while P2Y(6) did not contribute.

Adenosine Triphosphate↗

Positive inotropic responses mediated by endothelin ET(A) and ET(B) receptors in human myocardial trabeculae.

The aim of the present study was to determine possible inotropic effects mediated by endothelin ET(A) and ET(B) receptors in human myocardial trabeculae from the right atrium and the left ventricle. Isolated trabeculae from human hearts were paced at 1.0 Hz in tissue baths, and changes in isometric contractile force upon exposure to agonist were studied. Endothelin-1 (ET-1) and ET-3 had a strong positive inotropic effect in all trabeculae. ET-1 was significantly more potent than ET-3 in both atrial (P < 0.001) and ventricular (P < 0.05) trabeculae. Preincubation with the ET(A) receptor antagonist FR139317 (1 microM) decreased significantly (P < 0.005) the potency of ET- I in both atrial and ventricular trabeculae, without any significant changes in Emax (maximum effect obtained with an agonist). The ET(B) receptor agonist IRL 1620 had a positive inotropic effect only in some trabeculae, and the ET(B) receptor antagonist BQ 788 (1 microM) almost completely blocked this effect. These results suggest that both ET(A) and ET(B) receptors mediate positive inotropic responses at both the atrial and ventricular level in the human heart.

Adolescent↗

Angiotensin II type 1 receptors stimulate protein synthesis in human cardiac fibroblasts via a Ca2+-sensitive PKC-dependent tyrosine kinase pathway.

The aim of the present study was to investigate the proliferative effects of Ang II in human cardiac fibroblasts. The effects of Ang II in human cardiac fibroblasts on the 3H-thymidine incorporation, the cell number, the 3H-leucine incorporation and the total protein content were measured. The expression of receptor mRNA was performed by reverse transcription-polymerase chain reaction (RT-PCR). Ang II increased 3H-leucine incorporation in a concentration-dependent manner but not 3H-thymidine incorporation in primary cultures of human cardiac fibroblasts. The maximum effect (24 +/- 3% over control) was obtained at a concentration of 10 nM. There were no significant alterations of cell number or total protein content, suggesting that Ang II stimulated protein synthesis but did not induce hypertrophy. The accumulation of 3H-leucine was blocked by the AT1 receptor antagonist candesartan but not by the AT2 receptor antagonist PD123319. By using RT-PCR, both AT1 and AT2 receptors mRNA were found to be expressed in human cardiac fibroblasts. The selective MAPKK inhibitor PD098059, the protein kinase C inhibitor K252a or the phospholipase C inhibitor U73122 did not significantly inhibit Ang II augmented 3H-leucine incorporation. However, this was significantly blocked by the Ca2+-dependent protein kinase C inhibitor GO6976, the non-selective protein kinase inhibitor staurosporine and the tyrosine kinase inhibitor tyrphostin 25. The effects of Ang II were unaffected by the Gi-protein blocker pertussis toxin, indicating a Gi-protein-independent pathway. Ang II was synergistic with insulin but showed no significant increase on 3H-leucine incorporation when combined with PDGF or EGF. In summary, Ang II stimulates protein synthesis through AT1 receptors in human cardiac fibroblasts, but has no hypertrophic or hyperplastic effect. The response is mediated by a MAPKK-independent and Ca2+-sensitive PKC-dependent pathway.

Angiotensin II↗

Forearm blood flow responses to neuropeptide Y, noradrenaline and adenosine 5'-triphosphate in hypertensive and normotensive subjects.

Neuropeptide Y (NPY), noradrenaline (NA) and adenosine 5'-triphosphate (ATP) are important co-transmitters in the sympathetic nervous system, which has a central role in cardiovascular control. In order to evaluate if hypertension is associated with alterations in vascular responses to sympathetic co-transmitters we studied the effects of intra-arterial infusion of NPY, NA and ATP on forearm blood flow. Blood flow was measured by venous occlusion plethysmography in six hypertensive (mean arterial blood pressure (MAP) 113 +/- 4 mmHg) and six matched normotensive subjects (MAP 97 +/- 3 mmHg). NPY and NA significantly reduced forearm blood flow, while a powerful increase was seen with ATP. Forearm vascular resistance, calculated as MAP divided by forearm blood flow, was significantly increased by NPY and NA and strongly reduced by ATP. There was no difference between hypertensive and normotensive subjects in response to either transmitter. In conclusion, vascular reactivity to intra-arterial administration of NPY, NA and ATP seems to be intact in hypertensive patients without metabolic aberrations.

Adenosine Triphosphate↗

Downregulation of adenosine and P2X receptor-mediated cardiovascular responses in heart failure rats.

Neurohormonal changes in congestive heart failure (CHF) include an enhanced peripheral sympathetic nerve activity which results in increased release of noradrenaline, neuropeptide Y and ATP. To examine if such changes in CHF would modulate peripheral pre- and postsynaptic receptors of ATP and its degradation product adenosine, experiments were performed in a rat model of ischaemic CHF. In this model, ischaemia was induced in rats by ligation of the left coronary artery. Our results demonstrate that there is a selective downregulation of P2X receptor-mediated pressor effects, while the hypotensive effects mediated by the endothelial P2Y receptors are unaffected in CHF. Moreover, the adenosine-mediated inhibitory effects on heart rate and blood pressure were also attenuated in the CHF rats. The most important changes in adenosine and P2-receptor function induced by ischaemic CHF were the reduced pressor effect mediated by the P2X receptor and the increased heart rate due to an attenuated inhibitory effect of adenosine.

Adenosine↗

Inotropic effects of endothelin compared to noradrenaline in porcine myocardial trabeculae.

Isolated porcine myocardial trabeculae from the right atria and left ventricles were paced at 1.5 Hz in tissue baths, and changes in isometric contractile force upon exposure to noradrenaline (NA), endothelin-1 (ET-1) and endothelin-3 (ET-3) were studied. The endothelin-B- (ET(B)) receptor agonists IRL 1620 and sarafotoxin S6c (S6c), and the endothelin-A- (ET(A)) receptor antagonist FR139317 were used to assess the functional involvement of ET(A)- and ET(B)-receptors. NA, ET-1 and ET-3 induced strong increases in contractile amplitude of all trabeculae. In both atrial and ventricular trabeculae the increases in contractile amplitudes induced by ET-1 and ET-3 were significantly lower than those induced by noradrenaline, whereas the potencies for ET-1 and ET-3 were significantly higher than those for noradrenaline (p < 0.05, n = 6-10 in each group). The positive inotropic effect of ET-1 was antagonized by preincubation with FR139317 (10(-6) M). IRL 1620 had a positive inotropic effect in only a few of the ventricular but in none of the atrial trabeculae, and S6c had no positive inotropic effect in either atrial or ventricular trabeculae (n = 6-9 in each group). These results suggest that positive inotropic responses can be mediated by both ET(A)- and ET(B)-receptors.

Animals↗

Cytokines induce upregulation of vascular P2Y(2) receptors and increased mitogenic responses to UTP and ATP.

P2Y(2) receptors, which mediate contractile and mitogenic effects of extracellular nucleotides in vascular smooth muscle cells (VSMCs), are upregulated in the synthetic phenotype of VSMCs and in the neointima after balloon angioplasty, suggesting a role in the development of atherosclerosis. Because released cytokines in atherosclerotic lesions mediate multiple effects on gene transcription in VSMCs, we speculated that cytokines could be involved in the regulation of P2Y(2) receptor expression. Using a competitive reverse transcription-polymerase chain reaction, we detected that interleukin (IL)-1beta induced a time- and dose-dependent upregulation of P2Y(2) receptor mRNA, which was dramatically enhanced when combined with interferon-gamma or tumor necrosis factor-alpha. Lipopolysaccharide also significantly increased the expression of P2Y(2) receptor mRNA. The upregulation of P2Y(2) receptor mRNA was paralleled at the functional level because IL-1beta significantly increased the UTP-stimulated DNA synthesis and the release of intracellular Ca(2+). Actinomycin D completely blocked the upregulation of P2Y(2) receptor mRNA expression by IL-1beta, indicating de novo mRNA synthesis. There was no cAMP accumulation in the cells stimulated with IL-1beta. The cyclooxygenase inhibitor indomethacin and the protein kinase C inhibitor RO-31-8220 inhibited IL-1beta-induced upregulation of P2Y(2) receptor mRNA expression, whereas rapamycin and PD098059 had no effects. Furthermore, neither P38 mitogen-activated protein kinase inhibitor SB20358 alone nor its combination with PD098059 blocked the effect of IL-1beta on the expression of P2Y(2) receptor mRNA. Our results demonstrate that inflammatory mediators upregulate vascular P2Y(2) receptors at the transcriptional and at the functional level through protein kinase C and cyclooxygenase but not cAMP, extracellular signal-regulated kinases 1 and 2, or P38-dependent pathways. This may result in increased growth-stimulatory or contractile effects of extracellular UTP and ATP, which may be of importance in the development of vascular disease.

Adenosine Triphosphate↗