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Biomedical subjects

F Lembeck

Publications and source records attributed to F Lembeck.

At least 127 records · Page 7Linked to original sources
PubMed1981

In vitro release of substance P from spinal cord slices by capsaicin congeners.

The in vitro release of immunoreactive substance P (I-SP) by capsaicin and three congeners was studied on slices of rat spinal cord upper dorsal horn. Capsaicin and its congeners were all able to stimulate I-SP release, indicating that they act on chemosensitive primary afferents terminating in this region. A positive correlation was found between the I-SP releasing and pain-producing potencies of these compounds. This is in agreement with the concept that primary afferents containing substance P (SP) are involved in the transmission of nociceptive information.

Animals↗
PubMed1981

Determination of capsaicin in tissues and separation of capsaicin analogues by high-performance liquid chromatography.

Capsaicin, the pungent principle of chili peppers, and six analogues were characterized by reversed-phase high-performance liquid chromatography using isocratic methanol--water mixtures and UV detection. A highly sensitive method for the quantitative determination of capsaicin in animal tissues and blood has been developed. Using a reversed-phase column and acetonitrile--water mixtures for elution, 3 ng of capsaicin could be measured by fluorimetric detection at an excitation wavelength of 270 nm and an emission wavelength of 330 nm. Acetone extraction of tissue resulted in a recovery of approximately 90%. Extraction and determination of capsaicin in rat brain, spinal cord, liver and blood after i.v. administration is given as an example.

Animals↗
PubMed1981

Substance P in the argentaffin carcinoid of the caecum: biochemical and biological characterization.

An argentaffin carcinoid tumour of the caecum which contained serotonin (167 micrograms/g) and consisted predominantly of EC1-cells, was analysed for the presence of peptides using immunohistochemical, biochemical and pharmacological methods. A very high content of 3.9 micrograms/g of immunoreactive substance P was found. The distribution of cells staining positively for substance P matched that of cells containing serotonin. While some immunoreactive somatostatin (3.2 ng/g) was present in the tumour, neurotensin, glucagon, gastrin, and motilin were not found. Part of the substance P immunoreactivity measured most likely represents authentic substance P: it behaved like substance P in two chromatographic systems and in two bioassays, and its activity on the guinea pig ileum was abolished by specific tachyphylaxis towards substance P.

Carcinoid Tumor↗
PubMed1981

Substance P immunoreactive neurons following neonatal administration of capsaicin.

Neonatal administration of capsaicin on the days 2, 10 or 20 leads to a long-lasting loss of substance P immunoreactive material in fibers of primary sensory neurons in the spinal cord and medulla oblongata. The degree of depletion examined 6 months after treatment was related to the day of injection. Injections on the second day produced dramatic losses of substance P in fibers of the substantia gelatinosa and the marginal layer of the spinal cord and the spinal nucleus of the trigeminal nerve, although these losses were never complete. The observed depletion of substance P immunoreactive material was homogenous throughout the superficial layers of the dorsal horn and the spinal nucleus of the trigeminal nerve. No changes were observed for the immunoreactivity of Leu-enkephalin in the substantia gelatinosa and the marginal layer of the spinal cord in consecutive sections from the same treated animals. In the medulla oblongata a reduction of substance P immunofluorescent fibers was found in the nucleus tractus solitarii and the spinal nucleus of the trigeminal nerve. Other areas of the central nervous system with a rich innervation of substance P immunoreactive fibers were not affected by capsaicin treatment.

Animals↗
PubMed1981

Postocclusive cutaneous vasodilatation mediated by substance P.

1. The cutaneous vasodilatation following arterial occlusion ("reactive hyperemia") was studied in the rat hind paw. A peak increase in venous outflow of 200-250% was observed within 1 min after a 3 min occlusion period. 2. Chronic denervation as well as capsaicin pretreatment reduced the postocclusive cutaneous vasodilatation by more than 60% (P less than 0.01). This demonstrates that the reactive vasodilatation is of neurogenic origin and mediated by small diameter afferent fibres. 3. Reduction of the postocclusive cutaneous vasodilatation after histamine depletion by compound 48/80 indicates the involvement of histamine. 4. Among all neuropeptides known to occur in primary sensory neurones only substance P and vasoactive intestinal polypeptide cause vasodilatation when infused i.a. into the rat paw. In contrast to antidromic sensory nerve stimulation or i.a. substance P infusion, vasoactive intestinal polypeptide does not cause plasma extravasation. The vasodilator potency of vasoactive intestinal polypeptide is about 1/500 of substance P in the rat paw. Therefore only substance P is able to mimic the reactive vasodilatation. 5. It is concluded that the postocclusive cutaneous vasodilatation is caused mainly by the release of substance P from peripheral endings of small diameter nerve fibres. The "axon reflex", also involving neurogenic vasodilatation, is assumed to be exerted by the same mechanism.

Animals↗
PubMed1981

Time course of capsaicin-induced functional impairments in comparison with changes in neuronal substance P content.

1. Changes in the content of substance P (dorsal spinal cord, dorsal roots, dorsal root ganglia, saphenous nerve, skin) and functional changes (neurogenic plasma extravasation, chemosensitivity of the cornea) were measured in the rat from 10 min to 4 days after the s.c. injection of a single dose of 50 mg kg-1 capsaicin. 2. The substance P content in dorsal roots, saphenous nerve and hind paw skin progressively declined to about 60--70% of control 4 days after treatment, whereas that of the dorsal root ganglia rose, after an initial decline, to 140% after 1--4 days. 3. After denervation, impairment of neurogenic plasma extravasation could be observed not earlier than after one day, thus being comparable in time course to the depletion of substance P in the skin and saphenous nerve. 4. Neurogenic plasma extravasation and the chemosensitivity of the cornea were greatly diminished already 10 min after systemic capsaicin treatment, i.e. at a time when the substance P content of the peripheral nerve was still unchanged. These early effects of systemic capsaicin treatment are therefore caused by actions other than depletion of substance P.

Animals↗
PubMed1981

Release of histamine by substance P.

1. The basic peptide substance P causes histamine release from peritoneal mast cells of the rat in vitro whereas the closely related neutral peptides eledoisin and physalaemin do not. 2. Infusion of substance P (7.4 nmol min-1), but not of eledoisin (8.4 nmol min-1) or physalaemin (7.9 nmol min-1), into the rat hindquarter preparation caused a more than 4-fold increase of the histamine content in the venous outflow. The outflow of 5-HT remained unchanged under infusion of all three peptides. 3. No histamine depletion in the skin of the rat hind paw was observed following antidromic stimulation of the saphenous nerve or cutaneous application of mustard oil. Infusion of substance P (7.4 nmol min-1) caused a 47% depletion of histamine in the paw skin although only a small proportion of the infused substance P seemed to enter the tissue from the blood vessels. 4. The results further substantiate the view that substance P upon release from peripheral nerve endings induces release of histamine from cutaneous mast cells, a mechanism which contributes to neurogenic vasodilatation and plasma extravasation.

Animals↗
PubMed1981

Substance P in tumors: pheochromocytoma and carcinoid.

Immunoreactive substance P (I-SP) was measured in two pheochromocytomas and a carcinoid of the caecum. The pheochromocytomas contained 1,5 and 50 pmol/g I-SP respectively. An HPLC analysis I-SP and catecholamines were enriched in the chromaffin granule fraction. The carcinoid contained 2900 pmol/g I-SP. About 40% of the immunoreactivity behaved like substance P on gel filtration, HPLC and in bioassays (fall in rabbit blood pressure and contraction of the guinea-pig ileum which was abolished by specific tachyphylaxis to substance P). These results indicate that authentic substance P is present in carcinoids and pheochromocytomas and that in the latter it is most likely stored in chromaffin granules.

Adrenal Gland Neoplasms↗
PubMed1980

Requirement of nerve growth factor for development of substance P-containing sensory neurones.

The protein nerve growth factor (NGF) is known to be essential for the maturation and maintenance of adrenergic neurones and for the development of sensory neurones during critical stages of embryonic life. The investigation of the physiological importance of NGF for the development of sensory neurones has been hampered so far by the lack of biochemical marker substances for these neurones. The demonstration that the undecapeptide substance P(SP) is present in sensory neurones suggests that it might be such a marker. SP is synthesized in dorsal root ganglia (DRG) and transported to the terminals of C-fibres located in the dorsal horn of the spinal cord and in the skin. Its release can be demonstrated from the central and peripheral endings of sensory nerve fibres which seem to have an important role in pain perception. We have investigated the effects of NGF and of purified anti-NGF antibodies on the content of SP in rat DRG and in their respective target organs, namely the spinal cord and the skin. The effects on sympathetic ganglia were included in order to control the effectiveness of both NGF and its antibody. We report here that NGF leads to an increase in SP in spinal ganglia, as previously shown by Kessler and Black. However, in contrast to these authors, we describe that the administration of anti-NGF antibodies produces a marked reduction of the SP content in sensory neurones and in their respective nerve terminals.

Animals↗
PubMed1980

Distribution of substance P in the rat gastrointestinal tract--lack of effect of capsaicin pretreatment.

A new method for extraction of immunoreactive substance P (I-SP) from rat intestine including pulverization of tissue frozen in liquid nitrogen and extraction with acid acetone is described. Using this method, amounts of I-SP in the rat intestine were found to be higher than previously reported. The highest concentrations of I-SP were found in the small intestine. Capsaicin pretreatment of newborn or adult rats had no effect on intestinal I-SP concentrations indicating that intrinsic SP neurones are capsaicin-insensitive.

Animals↗
PubMed1980

Regional distribution and biochemical properties of 125I-Tyr8-substance P binding sites in synaptic vesicles.

1. Binding of 125I-Tyr8-substance P (SP) to synaptic vesicles shows an uneven distribution within the brain and the spinal cord. The regional distribution has a positive correlation with the SP-content, except in the hypothalamus. 2. Ca2+ and MG2+-ions (1 and 10 mM) decrease the number of binding sites without alteration of affinity. EDTA and EGTA enhance SP-binding which is interpreted as being due to removal of the inhibitory influence of endogenous Ca2+ and Mg2+ through chelation with these agents. No significant inhibition of SP binding was observed by Na+ or K+ in concentrations below 100 mM. 3. Pretreatment of synaptic vesicles with trypsin or with phospholipase A2, C and D leads to a total loss of SP binding showing a proteolipid or a joint protein-phospholipid nature of these binding sites. SH groups do not contribute to SP binding since no effect of N-ethylmaleimide and monoidoacetic acid on SP binding was found.

Animals↗
PubMed1980

Neurally mediated contraction of ileal longitudinal muscle by substance P.

The time course of the spasmogenic effect of substance P (SP) on the longitudinal muscle (LM) of the guinea-pig ileum was investigated. Maximum effective concentrations of SP (greater than or equal to 10 ng/ml) produced a fast initial response which subsequently declined to about 50% of the initial contraction. This remaining half-maximum contraction was increased by physostigmine and decreased by tropicamide, morphine, and tetrodotoxin; hexamethonium had no effect. The results indicate that SP, apart from its direct action on the LM, also activates cholinergic neurones innervating the LM.

Animals↗
PubMed1980

Substance P and opiate-like peptides in human adrenal medulla.

Opiate-like peptides (OLP), substance P (SP) and catecholamines (CA) were measured in 15 human adrenal medullae. Two groups of subjects were investigated. Group a consisted of subjects who died after traffic accidents and Group b consisted of subjects with other causes of death. OLP levels in Group a were only about 13%, and SP and CA levels about 50% of Group b. It is suggested that these differences might be due to massive premortal adrenal medullary discharge rather than post mortem degradation.

Adrenal Medulla↗