PubMed Health⌕ Search

Biomedical subjects

M Stjernquist

Publications and source records attributed to M Stjernquist.

At least 37 records · Page 2Linked to original sources
PubMed1994

Endothelium-dependent relaxation to substance P in human umbilical artery is mediated via prostanoid synthesis.

To investigate the relaxatory effect and mode of action of substance P in the human umbilical artery, ring segments of the artery were suspended in organ baths to record the circular motor activity. Substance P induced a significant relaxation in segments with intact endothelium pre-contracted by potassium or 5-hydroxytryptamine. Segments devoid of their endothelium failed to relax when challenged with substance P. The relaxation induced by substance P was inhibited by the cyclo-oxygenase antagonist indomethacin, while the nitric oxide-synthetase inhibitor L-NG-monomethyl-arginine was without effect. These findings suggest that the relaxatory effect of substance P in the human umbilical artery is dependent on an intact endothelium. In contrast to the case in most other vessels, the relaxation is not mediated via the release of endothelium-derived relaxing factor, but seems to be dependent on prostanoid synthesis.

Endothelium, Vascular↗
PubMed1993

Characterization of endothelin receptors and localization of 125I-endothelin-1 binding sites in human umbilical artery.

The mechanisms of endothelin-1-induced contractile response in the human umbilical artery were investigated in vitro. Autoradiography revealed 125I-endothelin-1 binding sites in the smooth muscle layer of the vessel wall. Endothelin-1 and sarafotoxin S6b induced concentration-dependent contractions while endothelin-3 was virtually without contractile effect. The endothelin ETA receptor antagonist BQ 123 did not affect the contraction to endothelin-1 but antagonized the contraction to sarafotoxin S6b. The contraction to endothelin-1 and sarafotoxin S6b was diminished by both verapamil and nicardipine. It can be concluded that endothelin-1 is a vasoconstrictor in the human umbilical artery, probably acting via more than one contraction-mediating receptor. The 125I-endothelin-1 binding sites demonstrated in the smooth muscle layer of the vessel may correspond to receptors mediating the contractile effect. The mechanisms of action seems to involve activation of Ca2+ channels. The present study does not give any evidence for interaction of endothelin-1 with other endothelium-derived vasoactive agents in this vessel.

Arginine↗
PubMed1993

Malaria in pregnancy--a master of masquerade.

One case of malaria in pregnancy at 23 weeks of gestation in a woman returning from Ghana is presented. The patient complained of diarrhea and abdominal pain and was admitted to the department of Gynecology and Obstetrics. Under suspicion of appendicitis an exploratory laparotomy was performed. Diagnosis was missed and treatment delayed five days. Outcome was favorable for both woman and fetus.

Abdominal Pain↗
PubMed1992

Contractile effect of endothelin in the human uterine artery and autoradiographic localization of its binding sites.

OBJECTIVE: The aim was to study the effects, mode of action, and binding sites of endothelin-1 in the human uterine artery. STUDY DESIGN: The contractile effect of endothelin-1 on the human uterine artery with and without endothelium and the effect of verapamil and nicardipine on the contraction was investigated in vitro. The Student t test was used. Iodine 125-endothelin-1 binding sites were localized with autoradiography. RESULTS: Endothelin-1 induced a contraction that was unaffected by removal of the endothelium. Verapamil antagonized the contraction, whereas nicardipine showed no effect. Iodine 125-endothelin-1 binding sites were demonstrated in the smooth muscle layer. CONCLUSIONS: These results show that endothelin-1 is a vasoconstrictor in the human uterine artery and suggest that the effect is mediated by receptors on the smooth muscle cells. The mode of action seems to involve Ca++ influx by other than dihydropyridine-sensitive Ca++ channels. Endothelin-1 does not seem to stimulate release of other endothelium-derived vasoactive agents.

Adult↗
PubMed1992

Smooth muscle dilatation in the human uterine artery induced by substance P, vasoactive intestinal polypeptide, calcitonin gene-related peptide and atrial natriuretic peptide: relation to endothelium-derived relaxing substances.

The relaxatory influences of substance P (SP), vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP) and atrial natriuretic peptide (ANP) were investigated in human uterine arteries precontracted by noradrenaline in vitro. SP, VIP, CGRP and ANP all relaxed isolated uterine arteries with intact endothelium. When tested on vessels devoid of their endothelium VIP and SP had no effect on smooth muscular tone, while ANP and CGRP still induced unchanged vasodilatation. These results suggest an involvement of an endothelium-derived relaxing substance in the mechanisms by which VIP and SP induce relaxation of the isolated human uterine artery. On the other hand, ANP and CGRP seem to act on the same vessel preparation in vitro independently of the vascular endothelium. Both addition of noradrenaline and exchange of sodium against potassium in the organ chambers resulted in smooth muscle contraction irrespective of the integrity of the endothelium.

Adult↗
PubMed1991

Neuropeptide Y (NPY) co-exists with tyrosine hydroxylase and potentiates the adrenergic contractile response of vascular smooth muscle in the human uterine artery.

The human uterine artery was studied by immunocytochemistry and in vitro pharmacology. Nerve fibres containing immunoreactivity for neuropeptide Y (NPY) were encountered in the media, adventitia, smooth muscle layers and surrounding the vasa vasorum. Approximately 50% of the nerve fibres containing NPY also stored immunoreactivity for tyrosine hydroxylase (TH) and TH activity was found in no other fibres. Noradrenaline (NA) contracted the isolated uterine artery in a concentration dependent manner. The presence of increasing doses of NPY shifted the concentration-response curve for NA to the left. Consequently the pD2-values were increased indicating a potentiation of the adrenergic effects induced by NPY. The results demonstrate the existence of NPY in adrenergic nerve fibres surrounding the human uterine artery. A close co-operation between NPY and NA in the neuronal control of smooth muscle is suggested.

Adult↗
PubMed1990

Adrenoceptors mediating contraction in the human uterine artery.

Pharmacological characterization of adrenoceptors mediating smooth muscle contraction was performed in isolated preparations from the human uterine artery. The mixed alpha 1- and alpha 2-adrenergic agonist, noradrenaline (NA) and the selective alpha 1-agonists, phenylephrine and methoxamine, all contracted the smooth muscle preparations in a concentration-dependent manner. The responses were antagonized competitively by the selective alpha 1-antagonist, prazosin, yielding pA2 values for the three agonists (8.33-9.08) typical for an interaction with alpha 1-receptors. The alpha 2-selective receptor agonists, clonidine and BHT 920, did not exert any contractile effects in the isolated uterine arteries, and the alpha 2-adrenergic antagonist, yohimbine, counteracted the contractile effect of NA only at high concentrations. The concentration-response curve for NA was unaffected by the alpha 2-selective antagonists, rauwolscine and idazoxan. The results suggest that the postjunctional contractile receptors in the human uterine artery primarily are of the alpha 1 type, and give no evidence for any substantial involvement of alpha 2-receptors in this important tributary vessel of the human female reproductive tract.

Adult↗
PubMed1988

Immunocytochemical localization of galanin in the rat male and female genital tracts and motor effects in vitro.

Galanin, a recently discovered neuropeptide, was studied in the rat male and female reproductive tracts by immunocytochemistry and in vitro pharmacology. Nerve fibers containing galanin immunoreactivity were most abundant in the female paracervical tissue, where they surrounded non-immunoreactive ganglion cells. Galanin nerves were also found in the uterus and Fallopian tubes, as well as in the vas deferens. When tested in vitro galanin contracted the smooth muscle of both the uterine horn and cervix. Galanin also slightly potentiated the response to electrical field stimulation in preparations from the uterine cervix and vas deferens, but it had no effect on the seminal vesicle. Galanin-(1-10), an N-terminal residue of galanin, also contracted the uterine horn, though higher concentrations were required. The neurally induced contractions were not influenced by galanin-(1-10) in any of the smooth muscle preparations tested. The muscle receptors mediating the direct contractile effects in the uterine horn seem to require the N-terminus of galanin, while the neuromodulatory effects on the electrically induced contractile activity seem to need the C-terminal part or the whole galanin molecule. Galanin may thus function as a neuromediator in the rat male and female genital organs.

Animals↗
PubMed1987

Coexistence and cooperation between neuropeptide Y and norepinephrine in nerve fibers of guinea pig vas deferens and seminal vesicle.

Fluorescence immunocytochemistry of guinea pig vas deferens and seminal vesicle revealed dense networks of nerve fibers containing both neuropeptide Y (NPY) and dopamine-beta-hydroxylase (DBH), a marker for adrenergic neurons. The effects of norepinephrine (NE) and NPY on the smooth musculature of these organs were studied in vitro. NE inhibited the response to electrical nerve stimulation and increased the basic tension in the vas deferens and contracted the smooth muscle of the seminal vesicle, but had no effect on the contractile response to transmural stimulation in the latter organ. NPY had similar effects on the vas and vesicula, i.e. it inhibited the electrically induced contractions and had no effect on the basic tension. The results suggest a role for NPY as a transmitter that acts before the site of the neuromuscular junction to modulate the release of other transmitters from motor nerve fibers in the smooth musculature.

Animals↗
PubMed1987

Interaction of noradrenaline, NPY and VIP with the neurogenic cholinergic response of the rat uterine cervix in vitro.

Quantitative pharmacological studies were performed on isolated uterine cervix which was obtained from oophorectomized and oestrogen-treated rats and therefore showed no spontaneous contractility. The concentration-response curves to ACh and carbacholine were to a varying degree depressed and right-shifted in the presence of NA, but not NPY or VIP. The electrically induced cholinergic contraction was potentiated in tissues from animals pretreated with reserpine or 6-OHDA, but only at high stimulation frequencies. Histochemically, both sympatholytics abolished NA from the cervical fibres, whereas immunoreactive NPY was still encountered. Tyramine in the organ bath reduced the contraction amplitude during electrical nerve stimulation concentration-dependently by a beta-adrenoceptor-sensitive mechanism. In the presence of neostigmine the amplitude was reduced by NA, but not by NPY or VIP, which, on the other hand, had an inhibitory effect in the absence of neostigmine. The results offer further support for the view that, although the cervical smooth muscle cells are equipped with adrenoceptors, the neurogenic motor response at low stimulation frequencies (around 3 HZ) is mainly cholinergic. It appears that neurally released NA is able to influence these muscle cells primarily at high frequencies. There is no clear-cut evidence that the inhibitory effects of neural NPY or VIP on the cervix of spayed, oestrogen-treated rats are mediated by postjunctional receptors.

Acetylcholine↗
PubMed1986

Existence and coexistence of peptides in nerves of the mammalian ovary and oviduct demonstrated by immunocytochemistry.

The immunocytochemical distribution of substance P (SP), gastrin releasing peptide (GRP), vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), and neuropeptide Y (NPY) was studied in the ovary and the Fallopian tube (oviduct) of rats, guinea-pigs, cows, pigs and humans. Generally, the nerve supply was better developed in the oviduct than in the ovary. GRP fibers were most scarce in all tissues. Nerves containing SP were particularly numerous in the oviduct of rat and guinea-pig, supplying the muscular wall and blood vessels. VIP and PHI coexisted in dense plexuses of nerves, not only around blood vessels but also in the follicular wall and the interstitial gland of the ovary, as well as within the smooth muscle layers and subepithelially in the oviduct. The general distribution of NPY was similar, but these immunoreactive nerves were even more numerous. Sequential staining for dopamine-beta-hydroxylase and NPY together with results of chemical sympathectomy with 6-hydroxydopamine suggested that NPY was stored in the noradrenergic sympathetic nerves.

Animals↗
PubMed1986

Neuronal localization and motor effects of gastrin-releasing peptide (GRP) in rat uterus.

All parts of the internal female reproductive tract of the rat contained nerve fibers with immunocytochemically visible gastrin-releasing peptide (GRP)-like material. GRP-like immunoreactivity was also seen in nerve cell bodies of the paracervical ganglion formation, which in addition, harboured GRP nerve fibers. Pharmacological experiments were performed on isolated uterine and cervical smooth muscle tissue from two groups of spayed animals, one of which received estradiol. Both GRP and its non-mammalian counterpart, bombesin, evoked concentration-dependent clonic contractions in uterus and cervix, most pronounced in the estrogen-treated animals. Bombesin induced a stronger contractile force than GRP. The responses were not affected by tetrodotoxin. The observations suggest that GRP may be one of several neural messengers involved in the control of uterine motor activity.

Animals↗
PubMed1986

Histochemical demonstration of a concomitant reduction in neural vasoactive intestinal polypeptide, acetylcholinesterase, and noradrenaline of cat uterus during pregnancy.

Noradrenaline, acetylcholinesterase, and vasoactive intestinal polypeptide (VIP) were visualized in uterine nerves of cats by histochemical techniques. Alterations were followed in different regions of the organs at various stages of pregnancy and compared with the situation in non-pregnant controls. Positively stained nerve fibres, the adrenergic type being particularly well developed, were found along the muscle bundles and around blood vessels in the smooth muscle layers, as well as in the mucosa, of both uterine horns and cervix. The nerve supply was especially prominent in the upper part of the cervix. The distribution of VIP-immunoreactive and acetylcholinesterase-positive nerve fibres resembled each other, but they were less numerous than the adrenergic fibres. In the course of pregnancy there was a marked reduction in the number of all positively reacting nerves, so that almost no fibres were visible in the uterine horns near term. A small number of positive nerve fibres was found to remain, however, in the wall of the sterile (empty) horn during unilateral pregnancy. The reduction was less prominent in the cervix, particularly its lower part. Distinct changes were encountered already during early and mid pregnancy in those parts of the uterine wall distended by the growing conceptus, where almost no fibres were seen. The nerve supply was more intact in the non-distended portions located between the fetuses, and especially in the empty horn of unilateral pregnancy. No overt reduction in the number of positively stained nerve fibres was found in the cervix at these pregnancy stages. The results show that marked alterations take place in the uterine autonomic innervation during such an entirely physiological event as pregnancy. There is reason to assume that the histochemical observations reflect both structural and functional alterations in the innervation related both to the type of nerves involved and to the localization of the conceptus.

Acetylcholinesterase↗
PubMed1986

Comparative histochemical distribution of nerve fibres storing noradrenaline and neuropeptide Y (NPY) in human ovary, fallopian tube, and uterus.

Nerves containing noradrenaline were studied by formaldehyde-induced fluorescence and neuropeptide Y (NPY) was visualised by immunohistochemistry in the human ovary, Fallopian tube and uterus. All structures were richly supplied with noradrenergic fibres closely associated with the vascular and non-vascular smooth musculature. NPY-containing nerve terminals were consistently fewer, particularly in the ovary. The best developed nerve supply was found in the tubal isthmus and uterine cervix. Vessels were usually innervated by plexuses of nerves, containing NPY as well as noradrenaline. The discrepancy between the number of the two types of histochemically distinguishable nerves suggests that, if noradrenaline and NPY are co-localised in one and the same nerve, this is not a constant phenomenon in the human female reproductive tract.

Fallopian Tubes↗
PubMed1985

Levels of neural vasoactive intestinal polypeptide in rat uterus are markedly changed in association with pregnancy as shown by immunocytochemistry and radioimmunoassay.

Immunocytochemical studies have shown that the rat uterus is well innervated by nerve fibers containing vasoactive intestinal polypeptide (VIP). The fibers were associated with both vascular and nonvascular smooth muscle cells, and they were somewhat more numerous in the cervix compared to the uterine horns. This was confirmed in radioimmunologic determinations. Pregnancy induced a marked, almost 50% reduction in the total content of VIP in the uterine horns, which was associated with an almost complete disappearance of immunocytochemically visible nerve fibers in this part of the uterus. The innervation normalized within 25 days following delivery. Less marked changes occurred in the VIP innervation of the cervical region, where the concentration of the peptide was reduced mainly as a result of the increased tissue weight during pregnancy.

Animals↗