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Biomedical subjects

R Schulz

Publications and source records attributed to R Schulz.

At least 559 records · Page 31Linked to original sources
PubMed1981

Are there subtypes (isoreceptors) of multiple opiate receptors in the mouse vas deferens?

The hypothesis of heterogeneity of opiate receptors was tested with the electrically stimulated mouse vas deferens. The experimental approach was based on the phenomenon of tolerance development of selective opiate receptors. It was found that opioids classified as mu-receptor agonists, e.g. sufentanyl and normorphine, do not necessarily exhibit cross-tolerance to each other. The same holds true for a variety of presumed kappa-receptor agonists. On the other hand, the delta-receptor agonists under investigation displayed complete cross-tolerance. These findings give rise to an interpretation which may postulate the existence of subtypes (isoreceptors) of the already known opiate receptors.

Animals↗
PubMed1981

[Endorphins].

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Endorphins↗
PubMed1981

Differentiation of opiate receptors in the brain by the selective development of tolerance.

The selective development to either the delta-opiate receptor agonist D-Ala2,D-Leu5-enkephalin (DADL) or the mu-agonist sufentanyl (SUF) has been studied in the central nervous system of rats by use of osmotic minipumps for chronic administration of the drugs. The opiate-sensitive parameters analgesia and catatonia were investigated. Chronic intracerebroventricular infusion of DADL for 7 days produced a 15-fold shift in that for catatonia. In these rats, the potency of SUF in inducing analgesia and catatonia did not differ between DADL-treated animals and saline-infused controls. Similarly, chronic infusion of SUF resulted in tolerance towards SUF for both analgesia and catatonia. In these animals, DADL displayed a similar degree of tolerance w.r.t. its ability to evoke analgesia, whilst no tolerance could be detected for DADL-induced catatonia. The data indicate that prolonged stimulation of specific opiate receptors in the brain by selective agonists may bring about the selective development of tolerance for particular receptors. The data conflict with the notion that mu-receptors specifically mediate analgesia and delta-receptors catatonia.

Animals↗
PubMed1981

Pharmacological characterization of the epsilon-opiate receptor.

The epsilon-opiate receptor of the electrically stimulated rat vas deferens has been characterized by means of beta-endorphin, its fragments and derivatives thereof, as well as by its tolerance development. The data provide evidence for the uniqueness of the epsilon-receptor as compared to mu- and delta-receptors of the guinea-pig ileum and the mouse vas deferens, respectively. It appears that an activation of the epsilon-receptor requires at least the beta-endorphin sequence 1-21, which sharply contrasts with the relatively high sensitivity of mu- and delta-receptors to much shorter fragments of this opioid peptide. Furthermore, after chronic exposure of rats to etorphine, the isolated vas deferens shows a dramatic loss of sensitivity to mu-receptor agonists, but only a moderate decrease in sensitivity to beta-endorphin. The presented data contribute to the characterization of a distinct novel type of opiate receptor, the epsilon-receptor.

Animals↗
PubMed1981

Functional opiate receptors in the guinea-pig ileum: their differentiation by means of selective tolerance development.

A differentiation of multiple opiate receptors in the electrically stimulated longitudinal muscle-myenteric plexus preparation of the guinea-pig ileum is described employing the technique of tolerance development of selective opiate receptors. Apparently, mu- and kappa-opiate receptors are clearly differentiated in this tissue, since highly tolerant mu-receptors (80-fold) coexist with kappa-receptors of almost normal sensitivity and vice versa. Attempts to demonstrate delta-receptors failed, as there was complete cross-tolerance between mu- and delta-agonists. It is proposed that delta-agonists bring about their action via mu-receptors in this preparation. Although mu- and kappa-receptors have been demonstrated, neither of them appear to represent a uniform population.

Animals↗
PubMed1981

[Report of experiences with ambulatory cytostatic chemotherapy in germinal testicular tumors and metastasizing renal carcinomas].

Today, the cytostatic chemotherapy is a firm constituent in the treatment plan of the germinal tumours of the testicles. In metastasizing renal carcinomas the attempt of treatment seems to be justified. The chemotherapy must be performed as a combined chemotherapy in interval during at least two years. From this result various problems for the patient as well as for the treating clinic. The patients often take an unreasonable attitude to the repeated long-term hospital treatment. Here, the ambulatory chemotherapy, at first carried out in consequences of a certain emergency situation, is a true alternative. After an experience of two years with this method we may recommend the ambulatory cytostatic chemotherapy. The rates of remission correspond to those of hospital cures, where the wellbeing of the patients wtih ambulatory therapy must be emphasized.

Adenocarcinoma↗
PubMed1981

[Results of percutaneous kidney cyst sclerosing].

The results of the percutaneous obliteration of the renal cysts in 68 renal cysts (6 cases of recidivation) are discussed. The use of an obliteration remedy is superior to the only submaximal depletion of cysts. The results after the sclerosation treatment with ethoxysclerol 2% were essentially better than after varicocid instillation. The sclerosation therapy may be performed only after a preliminary thorough angiographical clarification including renocystography. The excretion urograms are sufficient for the control examination.

Angiography↗
PubMed1980

Opiate activity and receptor selectivity of dynorphin1-13 and related peptides.

Experiments on the mouse vas deferens preparation obtained from animals chronically pretreated with selective opioid agonists have revealed the existence of opiate receptors with a high degree of preference for dynorphin1-13, alpha-neoendorphin1-8 and the eta-agonist MR 2034. Modification of the dynorphin sequence, by introduction of D-alanine into position 2, resulted in a complete loss of dynorphin-like agonistic activity on the tolerant mouse vas deferens. None of the dynorphin-related peptides tested displayed a pronounced opiate-like antinociception when administered intracerebroventricularly into rats.

Animals↗