Biomedical subjects

L Edvinsson

Publications and source records attributed to L Edvinsson.

At least 253 records · Page 14Linked to original sources

PubMed1992

Evidence for multiple endothelin receptors in the guinea-pig pulmonary artery and trachea.

1. The responses of the three peptides, endothelin 1 (ET-1), endothelin 2 (ET-2) and endothelin 3 (ET-3) were analysed on isolated circular segments of pulmonary arteries and trachea from the guinea-pig. 2. In the pulmonary artery, the vasomotor responses to the endothelins, expressed as the maximum contraction (Emax%), had the order ET-1 greater than ET-2 greater than ET-3 while the order of potency (pD2) was ET-1 = ET-2 greater than ET-3. ET-1 and ET-2 caused cross-desensitization, but did not affect the responses to ET-3. ET-3 did not cause cross-desensitization to ET-1 or ET-2 although it induced homologous desensitization. Finally, the effects of ET-1 and ET-2 were additive to those of ET-3. The additive effect of ET-3 to those of ET-1 or ET-2 was more difficult to demonstrate, given the profound contraction produced by ET-1 and to a lesser extent by ET-2. 3. In the trachea, the rank order of potency, additivity and desensitization were different from the pulmonary artery. Basically, all three peptides were equipotent but less potent than ET-1 in the artery. There was no evidence for additivity and only a slight tendency to tachyphylaxis was seen. 4. The guinea-pig pulmonary artery appears to be endowed with one receptor type which is sensitive to ET-1/ET-2 and with another receptor type which responds preferentially to ET-3. In the trachea, neither of these receptors appears to be present since all three peptides apparently act on a homogeneous population of receptors with characteristics different from those of the two arterial receptors. This suggests a third non-isopeptide selective type of endothelin receptor.

Animals↗

PubMed1992

Cardiovascular and renal effects of gamma-MSH in spontaneously hypertensive and normotensive Wistar Kyoto rats.

The objective of this study was to compare the cardiovascular and renal effects of the two gamma-melanocyte-stimulating hormone (MSH) peptide sequences in the pro-opiomelanocortin prohormone structure in conscious, anesthetized, and pithed spontaneous hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) controls. In the conscious but not in the pithed rats, intravenous injection of gamma 2- and gamma 1-MSH induced a rapid and dose-dependent increase in mean arterial pressure (MAP), and gamma 2-MSH was more potent than gamma 1-MSH. The pressor response was more pronounced and more sustained in the SHR compared with the WKY. There were dose-dependent and significant increases in heart rate (HR) after gamma 2- and gamma 1-MSH in the SHR. At intravenous infusions of low doses of gamma 2-MSH, which did not significantly influence MAP or HR, urinary sodium excretion was significantly increased in both SHR and WKY. In conscious, but not in anesthetized rats, intracerebroventricular administration of the gamma 2-MSH peptide induced sustained increases in MAP in both SHR and WKY. After intrathecal administration, there were transient pressor effects of gamma 2-MSH. We conclude that the pro-opiomelanocortin-derived gamma 2- and gamma 1-MSH peptide sequences possess potent rapid pressor actions. The pressor effects, which require an intact sympathetic nervous system, are more pronounced in the SHR strain. Moreover, gamma 2-MSH induces natriuresis when administered in nonpressor doses in WKY and SHR.

Anesthesia↗

PubMed1992

Inhibition of endothelin (ET-1) induced pressor responses by the endothelin (ETA) receptor antagonist FR139317 in the pithed rat.

The effects of the novel ETA receptor antagonist, FR 139317, on ET-1 induced blood pressure changes were studied in the pithed Sprague-Dawley rat. FR139317 in a dose of 0.025 mg/kg b.w. had no effect while 0.05-1 mg/kg b.w. dose dependently inhibited the pressor response to an i.v. bolus injection of ET6-1 (800 pmoles/kg). While FR139317 potently inhibited the magnitide and duration of the ET-1 induced pressor response, the ETA antagonist did not significantly influence the shortlasting initial depressor response. We conclude that FR139317 in the pithed rat potently inhibits ET-1 mediated pressor responses and that this agent may become a significant tool to elucidate the putative physiological and pathophysiological role of ETA receptor mediated responses.

Animals↗

PubMed1992

Sensory nerve terminal activity in severe hypertension as reflected by circulating calcitonin gene-related peptide (CGRP) and substance P.

In patients with severe hypertension and in age and sex matched controls the circulating levels of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) and substance P-LI were measured. Samples were taken before medication, after 2-4 weeks and 2-12 months of pharmacological treatment to normotension. In the control group CGRP-LI levels were significantly higher for females than for males. No such relation was seen for substance P-LI. There were no correlations between CGRP-LI, substance P-LI or blood pressure. In the untreated acute hypertensive group there was a significant correlation between circulating levels of CGRP-LI and both diastolic and systolic blood pressure. No such relationship was seen for substance P-LI. The plasma levels of substance P-LI were significantly elevated (2.8 +/- 4.0) compared to controls (1.3 +/- 1.3, pmol/l, mean +/- S.D., p < 0.01). The levels of CGRP-LI did not differ from the control group. After 2-4 weeks of treatment the blood pressure decreased significantly and the plasma levels of substance P-LI were normalized while the CGRP-LI still did not differ from that of controls. After 2-12 months of treatment the blood pressure was still normalized, and the plasma levels of CGRP-LI and substance P-LI were not different from the control group. In the present study there was a positive correlation in hypertensives between the circulating CGRP-LI levels and diastolic and systolic blood pressure and elevated levels of substance P-LI. This would implicate the existence of a dynamic control through which the sensory system may register and damp the pressure response.

Adult↗

PubMed1992

Calcitonin gene-related peptide (CGRP) activates human neutrophils--inhibition by chemotactic peptide antagonist BOC-MLP.

The effect of the neuropeptides substance P, neurokinin A and alpha-calcitonin gene-related peptide (CGRP) on human neutrophil granulocytes was investigated. Substance P induced secondary granule secretion at a concentration of 100 microM. CGRP induced a significant secretory response at 10 microM and thus appeared to be about 10 times more potent than substance P. Calcitonin and a fragment of CGRP, CGRP(8-37), had no effect on neutrophil degranulation. The chemotactic peptide antagonist BOC-MLP (100 microM) inhibited lactoferrin secretion mediated both by CGRP and chemotactic peptide FMLP almost completely, while secretion in response to tumour necrosis factor (TNF) was unaffected. Results from receptor binding studies showed that CGRP and N-formyl-methionyl-leucyl-phenylalanine (FMLP) do not compete for binding. This indicates that CGRP does not exert its effects by binding to the chemotactic peptide receptor. CGRP induced a rapid increase in the cytosolic-free calcium concentration and this increase was not, unlike that induced by FMLP, abolished by preincubation of the cells with pertussis toxin (1000 ng/ml). Therefore CGRP signal transduction in neutrophils appears to involve rapid changes in the cytosolic-free calcium concentration but not a pertussis toxin-sensitive G-protein. In summary, this is the first report to show that CGRP can directly activate neutrophil granulocytes, and this probably occurs via a cell surface receptor which is distinct from that of FMLP although both the CGRP and FMLP-mediated effects can be blocked by BOC-MLP.

Calcitonin Gene-Related Peptide↗

PubMed1992

Peptides as targets for antihypertensive drug development.

AIM: To assess the potential for development of new classes of pharmacological drugs in the treatment of hypertension and cardiovascular disease. BACKGROUND: Basis of pharmacological blood pressure reduction: Since the discovery of the renin-angiotensin system by Tigerstedt almost 100 years ago, a large number of vasoactive peptides have been discovered. By interaction with such peptides of endocrine, perivascular or endothelial origin, blood pressure may be modulated. BLOCKADE OF THE RENIN-ANGIOTENSIN SYSTEM: The success of the angiotensin converting enzyme (ACE) inhibitors in hypertension and congestive heart failure is generally attributed to reduced generation of angiotensin II. The recent development of specific and highly potent Ang II type 1 subtype receptor antagonists such as losartan (DuP753, MK954) have provided a new opportunity to inhibit the renin-angiotensin system, and this is currently being explored in hypertensive patients. In addition, blockade of the first and rate-limiting reaction of the renin-angiotensin system, inhibition of renin activity, is also a target for the development of antihypertensive drugs. However, this development is hampered at present by a compensatory increase in active renin that clinically offsets the antihypertensive action of renin inhibitors. PHARMACOLOGICALLY INDUCED INCREASE IN ATRIAL NATRIURETIC PEPTIDE (ANP): The availability of circulating or tissue ANP may be increased by inhibiting its metabolic clearance by NEP-24.11 inhibitor drugs. These agents induce a reduction in blood pressure and diuretic effects in animal models, and may become a new class of drugs for the clinical management of patients with hypertension and congestive heart failure. OTHER POTENTIAL PHARMACOLOGICAL TARGETS IN THE MANAGEMENT OF HYPERTENSION: There are several potential pharmacological targets that may lead to the development of novel antihypertensive agents in the future. These include the interaction or blockade of vasopressor peptides. Routes of development include neuropeptide Y1 receptor antagonists, which block the postjunctional vasopressor effect of neuropeptide Y, or endothelin antagonists, which block endothelin pressor actions at the endothelin A receptor site. The cardiovascular actions of the functional neuropeptide Y inhibitor alpha-trinositol (PP 56) provide a potential new mechanism for reducing blood pressure in hypertension. In addition, the recent discovery of small molecular agents with high potency and specificity for the endothelin A receptor subtype may also be of value in specific vascular disease states. CONCLUSIONS: Future development is likely to provide us with novel drugs based on interactions with vasoactive peptides that may improve the management of specific cardiovascular disease states.

Amino Acid Sequence↗

PubMed1992

Effects of d-myo-inositol-1,2,6-trisphosphate on neuropeptide Y-induced potentiation of various vasoconstrictor agents in the rat.

The adrenergic cotransmitter neuropeptide Y (NPY) induces vascular smooth muscle contraction by occupying postsynaptic Y1 receptors and by enhancing the vasoconstriction induced by a series of other pressor agents. In particular, NPY modulates the blood pressure response to alpha-1 adrenergic agonists and angiotensin II. The inositol phosphate derivative, d-myo-inositol-1,2,6-trisphosphate (PP56), is a novel NPY antagonist which within a defined dose range selectively blocks the effects of exogenously administered NPY in vivo. In the pithed animal as well as in the freely moving Sprague-Dawley rat, an i.v. bolus administration of PP56 (2 mg/kg) followed by an infusion (20 mg/kg/hr for 30 min) inhibited the approximate 50% increase in mean arterial blood pressure induced by a continuous infusion of NPY (2 micrograms/kg/min for 10 min). Furthermore, PP56 treatment completely inhibited the enhancement induced by NPY (0.1 microgram/min for 50 min or 2 micrograms/kg/min for 10 min) of the pressor responses to preganglionic sympathetic nerve stimulation (in the pithed rat) and to i.v. bolus injections of noradrenaline (20 ng), the indirect sympathomimetic tyramine (40 micrograms) as well as to angiotensin II (10 ng). These results show that PP56, representing a new class of synthetic nonpeptide drugs, is capable of antagonizing the vascular smooth muscle contractile as well as the potentiating effects of NPY in vivo in the pithed as well as the conscious rat.

Angiotensin II↗

PubMed1991

Effects of intracerebroventricular D-myo-inositol-1,2,6-trisphosphate (PP56), a proposed neuropeptide Y (NPY) antagonist, on locomotor activity, food intake, central effects of NPY and NPY-receptor binding.

D-myo-Inositol-1,2,6-trisphosphate (PP56) is a novel experimental drug which is structurally related to the intracellular second messenger IP3. Among other pharmacological effects, PP56 has been shown to antagonize neuropeptide Y (NPY) induced vasoconstriction with a high degree of specificity. We examined the effects of i.c.v. PP56 on locomotor activity and food intake in rats, and on the hypoactivity and hyperphagia induced by NPY. In the open field, PP56 given alone increased locomotor activity by up to 85%. It did not prevent NPY induced hypoactivity to any extent. PP56 given alone did not affect food intake except for a small increase after the highest dose tested (200 nmol). When NPY was given after pretreatment with PP56, NPY induced hyperphagia was significantly reduced. A similar effect, however, was seen with regard to the hyperphagia produced by another orexigenic peptide, galanin. PP56 did not affect the binding of 125I-NPY to brain membranes in vitro, or to cells of two different neuroblastoma cell lines which selectively express NPY Y1 or Y2 receptors. In summary, PP56 acted as a locomotor stimulant per se. Only one of the two tested central effects of NPY could be antagonized by PP56, and then only partially and in a non-specific manner. The central effects of PP56 do not seem to be produced at the level of NPY receptors.

Animals↗

PubMed1991

D-myo-inositol-1,2,6-trisphosphate is a selective antagonist of neuropeptide Y-induced pressor responses in the pithed rat.

The antagonistic effects of a new inositol phosphate derivative, D-myoinositol-1,2,6-trisphosphate (PP56), on pressor responses to preganglionic sympathetic nerve stimulation and exogenously administered phenylephrine or neuropeptide Y (NPY) were investigated in vivo in the pithed rat. In this model an intravenous (i.v.) bolus administration of PP56 (1-50 mg/kg) dose dependently inhibited the increase in mean arterial blood pressure (MAP) induced by a continuous infusion of NPY (2 micrograms/kg per min for 10 min). PP56 in a dose of 5 mg/kg i.v. bolus reduced the entire NPY dose-response curve (0.4-8 microgram/kg per min 10 min infusion) without any shift to the right indicating a non-competitive interaction. Furthermore, PP56 (10-50 mg/kg i.v.) was found to inhibit the pressor response to preganglionic sympathetic nerve stimulation and i.v. bolus injection of the alpha 1-adrenoceptor agonist, phenylephrine. The dose-response curves for increasing doses of phenylephrine and incremental preganglionic sympathetic nerve stimulation were not significantly altered by a lower dose of PP56 (5 mg/kg i.v. bolus). We conclude that PP56, representing a new class of synthetic drugs, can antagonize the actions of exogenous and endogenous NPY in vivo, an action which is specific for NPY within a limited dose range.

Analysis of Variance↗

PubMed1991

Increased plasma levels of neuropeptide Y-like immunoreactivity and catecholamines in severe hypertension remain after treatment to normotension in man.

Circulating levels of neuropeptide Y (NPY)-like immunoreactivity (-LI), adrenaline and noradrenaline (NA) were analysed in 17 patients admitted to the emergency ward due to severe hypertension; blood pressure mean 204/127 mmHg. The levels of NPY-LI and NA were significantly higher (P less than 0.001) in the hypertensives as compared to a normotensive control group. HPLC analysis revealed that the plasma contained besides NPY-LI also several NPY-LI fragments of low hydrophobicity. Following 2 to 3 weeks treatment the blood pressure had decreased to a mean of 150/89 mmHg. However, circulating levels of NPY-LI (P less than 0.001) and NA (P less than 0.01) were still significantly higher than in controls in spite of the marked reduction in blood pressure. Simultaneous measurements of adrenaline did not reveal any significant changes and these values did not differ compared with those in the normotensive subjects. The findings suggest that peripheral markers of the sympathetic system (NPY-LI and NA) in severe hypertension is not directly related to the blood pressure level.

Aged↗

PubMed1991

Reduced levels of calcitonin gene-related peptide-like immunoreactivity in human brain vessels after subarachnoid haemorrhage.

Human cerebral vessels were found to contain calcitonin gene-related peptide (CGRP)-like immunoreactivity (-LI) which in the reversed phase HPLC co-eluted with authentic human alpha-CGRP. The level was significantly lower in arteries removed from patients who had died from a subarachnoid haemorrhage (SAH) as compared to patients who died of a coronary infarction. On a molar basis human alpha-CGRP was more potent than human beta-CGRP to dilate human brain vessels and to dilate vasoconstriction elicited by whole blood. It is suggested that the trigemino-cerebrovascular system storing CGRP-LI may be involved in the pathophysiology of SAH in man.

Adult↗

PubMed1991

Comparison of the calcium entry blockers nimodipine and flunarizine on human cerebral and temporal arteries: role in cerebrovascular disorders.

The effect of the calcium entry blockers flunarizine and nimodipine on isolated human cerebral and temporal arteries has been studied. Flunarizine induced only weak relaxation of precontracted temporal arteries in contrast to the response seen in cerebral arteries. Nimodipine invariably induced strong relaxation of both types of vessel. The effect of the calcium entry blockers on potassium (K+)-, noradrenaline (NA)- and 5-hydroxytryptamine (5-HT)-induced contraction was also examined. In general, the K(+)-induced contraction was inhibited by both calcium entry blockers, nimodipine being more potent than flunarizine, the cerebral artery being more sensitive. The response to K+ consisted of two phases; the second, slowly developing phase of contraction was more sensitive to either blocker than the initial, fast phase of contraction. Flunarizine was significantly more potent in inhibiting NA-induced contraction of the human cerebral than of the temporal artery, and there was no difference in its action on 5-HT-induced contraction of either artery. The same pattern was found for nimodipine, which was more potent in every aspect. Both calcium entry blockers induced a parallel shift in calcium-induced contraction studied by application of calcium to vessels preincubated in calcium free medium. Flunarizine was more potent on cerebral than on temporal arteries and there was no difference between the two vessels in this action of nimodipine. However, the latter was more potent than flunarizine in preventing calcium-induced contraction. The clinical implications of the two agents are discussed in relation to cerebrovascular disorders.

Calcium↗

PubMed1991

Blockade of neuropeptide Y-induced potentiation of noradrenaline-evoked vasoconstriction by D-myo-inositol-1.2.6-trisphosphate (PP56) in rabbit femoral arteries.

Neuropeptide Y (NPY) potentiates noradrenaline (NA)-evoked constriction of circular segments of the rabbit femoral artery. The potentiation occurs exclusively in the lower concentration-range of the agonist NA (10(-8)-3 x 10(-7) M) without any change in maximum contractile effect. NPY per se is without contractile effect in the rabbit femoral artery. The recently developed substance, D-myo-inositol-1.2.6-trisphosphate (PP56), which is an isomer of inositol-1.4.5-trisphosphate, is without effect per se on the rabbit femoral artery, nor does it affect NA-induced contractions. However, it was found to completely antagonize NPY-induced potentiation of the NA concentration-response curve.

Animals↗

PubMed1991

Migraine: a research field matured for the basic neurosciences.

Progress in migraine research has been rapid in recent years, from both the basic science and the clinical perspectives. A new internationally accepted headache classification with operational diagnostic criteria was published in 1988, eliminating much diagnostic uncertainty. More than a decade of study of regional cerebral blood flow (rCBF) has gradually shown a pathognomonic pattern of abnormalities, probably reflecting spreading cortical depression. Recently it has been shown that pain probably arises from excitation of perivascular pial arterial nociceptors. The innervation and receptor mechanisms of pial and extracranial arteries have been worked out in detail both in animal and humans. Involvement of calcitonin gene-related peptide (CGRP) and 5-hydroxytryptamine (5-HT) during migraine attacks has been demonstrated. A new and specific 5-HT1D receptor agonist has proved to be highly effective in treating migraine. Therefore, major research efforts recently have been concentrated on discovering the location and function of 5-HT1D receptors, extra- and intracranially. Thus, it is now possible to formulate useful neuroscientific research strategies aimed at clarifying migraine mechanisms.

Animals↗

PubMed1991

Tachykinins (substance P, neurokinin A, neuropeptide K, and neurokinin B) in the cerebral circulation: vasomotor responses in vitro and in situ.

The vasomotor responses of tachykinins have been studied in the cerebral vasculature of human, pig, cat, and guinea pig. Substance P (SP), neurokinin A (NKA), neurokinin B (NKB), and neuropeptide K (NPK) induced concentration-dependent relaxations of precontracted cerebral arteries in all species when examined by a sensitive in vitro technique. In addition, the relaxant responses to SP, NKA, and NKB were studied in cat pial arterioles by peptide microapplication in situ. In human pial vessels, the order of relaxant potency was SP greater than NKB greater than NKA greater than NPK; in the pig middle cerebral artery, there was no difference in potency between the tachykinins; in the cat middle cerebral artery, SP = NKB greater than NKA = NPK; and in the guinea pig basilar artery, SP much greater than NPK = NKA greater than NKB. Responses induced by SP, NKA, and NKB in the cat were comparable in vitro and in situ. Removal of the endothelium abolished relaxation induced by all four tachykinins. The relaxant responses of guinea pig basilar arteries to SP, NKA, and NPK were competitively antagonized by the SP antagonist Spantide. However, Spantide lowered the Imax of the NKB concentration-response curve without any rightward shift, suggesting action at a different site than the other tachykinins. In the guinea pig basilar artery, the relaxation seems to be exerted via a NK-1 receptor subtype while the receptor subtype is more unclear in cerebral arteries from human, cat, and pig.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Histamine receptors in the isolated human middle meningeal artery. A comparison with cerebral and temporal arteries.

The subtypes of histamine receptors mediating dilatation of human meningeal arteries have been tested in vitro, using "selective" antagonists, and compared with cerebral and temporal arteries previously examined. Dilatory responses were tested after preconstriction with prostaglandin F2 alpha. Both mepyramine and cimetidine caused a parallel shift to the right of the histamine concentration-response curve, suggesting the presence of both H1- and H2-receptors. Combined treatment with mepyramine and cimetidine caused further displacement of the concentration-response curve to the right. Schild analysis indicated pA2 values of 6.3 for cimetidine and 9.8 for mepyramine in situations of near complete blockade of either of the receptors. Both H1- and H2-receptors seem of importance for the histamine-induced dilatation in meningeal arteries and neither appear to dominate. The data considered in conjunction with our previous findings support the finding that experimental histamine-induced headache due to vasodilatation is intracranial of origin.

Adult↗

PubMed1991

Increased plasma level of substance P in patients with severe congestive heart failure treated with ACE inhibitors.

The effects of angiotensin-converting-enzyme (ACE) inhibitors on circulatory regulating mechanisms in congestive heart failure (CHF) were studied by comparison of plasma levels of catecholamines, neuropeptide Y-like immunoreactivity (NPY-LI), substance P (SP-LI), calcitonin gene-related peptide (CGRP-LI), vasopressin (ADH-LI), atrial natriuretic peptide (ANP-LI) and renin activity (PRA) in patients with severe CHF (NYHA III-IV) with (n = 15) or without (n = 17) ACE inhibitors in addition to digoxin and diuretic therapy. Data were also compared with those for healthy subjects (n = 31) and patients with moderate CHF (NYHA I-II). Catecholamines and NPY-LI were increased to the same extent in both groups with severe CHF. CGRP-LI showed no changes relative to controls in any of the patient groups, and was not affected by ACE inhibitors. The SP-LI level was significantly increased in all patient groups. Patients with severe CHF on ACE inhibition had a SP-LI level of 4.05 +/- 0.79 pmol l-1, compared to a concentration of 2.28 +/- 0.30 pmol l-1 (P less than 0.05) in the patient group with a comparable degree of CHF but without ACE inhibition. In the latter group, an inverse relationship appeared between the SP-LI and the serum sodium levels (r = -0.68, P less than 0.05). The patients with severe CHF who received ACE inhibitors had significantly lower ADH-LI levels than the patients with a comparable degree of CHF who were not treated with ACE inhibitors, while the ANP-LI levels was increased to a similar extent in both groups.

Aged↗

PubMed1991

Neuropeptide Y and vasoactive intestinal peptide in experimental subarachnoid hemorrhage: immunocytochemistry, radioimmunoassay and pharmacology.

The involvement of noradrenaline (NA), neuropeptide Y, (NPY), 5-hydroxytryptamine (5-HT), acetylcholine (ACh) and vasoactive intestinal polypeptide (VIP) has been examined in the late phase of spasm after an experimental subarachnoid hemorrhage (SAH) in a rat model. Immunocytochemistry and radioimmunoassay of blood vessels from the circle of Willis did not show significant differences in NPY- and VIP-like immunoreactivity 2 days post SAH as compared to control vessels. The postjunctional effects of NA, NPY, 5-HT, ACh and VIP were studied two days after SAH using a sensitive in vitro system. NPY induced contractions were significantly (p less than 0.01) weaker (lower Emax) in SAH as compared to control rats while the relaxant responses to ACh and VIP were slightly increased after SAH. These observations reveal that in a rat model of SAH, with an approximately 20% in vivo constriction at two days, dynamic changes occur in cerebral artery reactivity despite any obvious change in sympathetic or parasympathetic perivascular nerve networks.

Acetylcholine↗