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Biomedical subjects

P F Schmidt

Publications and source records attributed to P F Schmidt.

9 recordsLinked to original sources
PubMed1991

Limitedly selective action of a delta-agonistic leu-enkephalin on the transmission in spinal motor reflex pathways in cats.

1. The influence of the delta-opioid receptor agonist (D-Ser2)-leu-enkephalin (Thr6) (DSLET) on different spinal reflex pathways was investigated in anaemically decapitated, high spinal cats. Monosynaptic reflexes were tested to analyse excitatory and inhibitory flexor reflex afferent (FRA) pathways from nociceptive (from the skin of the central pad) and non-nociceptive (from skin, joint or group II muscle) afferents, as well as an excitatory nociceptive non-FRA pathway from the central pad to plantaris and intrinsic foot extensors and the inhibitory pathway from Ib muscle afferents. 2. DSLET suffused over the spinal cord (concentration 10(-3)-10(-6) M) caused a concentration-dependent depression of transmission in nociceptive and non-nociceptive FRA pathways. The excitatory FRA pathways including those from group II muscle afferents were more sensitive than the inhibitory ones. The nociceptive non-FRA pathway from the central pad to plantaris and intrinsic foot extensors was less affected than the FRA pathways. The inhibitory pathway from Ib muscle afferents remained almost unaffected. 3. Intravenous injection of DSLET (0.5-3.6 mg/kg) induced dose-dependent effects similar to those from local spinal application. The main difference was that I.V. injection more readily caused depression of the inhibitory FRA pathways to extensors. 4. The effects of local spinal application and of I.V. injection of DSLET were antagonized by I.V. injection of naloxone (0.1-1 mg/kg). 5. The effects of DSLET on spinal reflex pathways in many respects resemble that of monoamines. Possibly there is an interaction and a co-operation of enkephalins and monoamines in motor control.

Afferent Pathways↗
PubMed1990

Polyneuropathy due to acute arsenic intoxication: biopsy studies.

A 41-year-old vintner attempting suicide ingested 8-9 g of arsenic and developed a symmetric polyneuropathy with acute Wallerian degeneration of myelinated fibers. Under treatment with modified British Anti-Lewisite (BAL; "Dimaval") his polyneuropathy slowly, but incompletely, subsided over three years at which time another sural nerve biopsy specimen showed regenerative proliferation of myelinated and unmyelinated axons but no signs of Wallerian degeneration. By laser microprobe mass analysis (LAMMA) arsenic was located in the first biopsied sural nerve specimen but not in the second specimen. These findings demonstrated: 1) arsenic induced serial morphometric and electron microscopic findings of nerve fiber degeneration and regeneration, 2) documentation of arsenic within myelinated nerve fibers, and 3) the usefulness of the LAMMA technique as a diagnostic procedure in this context.

Acute Disease↗
PubMed1989

Influence of the organophosphorus compound DFP on inhibitory motor systems and esterase activity in the spinal cord of cats.

In high spinal cats, the acute time-dependent changes of both the activity of spinal reflex pathways and the activity of three different esterases (acetylcholinesterase, carboxylesterase and neurotoxicant target enzyme) in the spinal cord were investigated after intravenous application of the organophosphorus compound di-isopropyl phosphofluoridate (DFP). There is no general depression of spinal reflexes by DFP. While the recurrent inhibition is completely abolished for a long time and the reflexes to a flexor (PBSt) are depressed but with a shorter recovery time, the reflexes to an extensor (GS) are distinctly less depressed or even facilitated. Reflex pathways from skin afferents to motoneurones did not react in a uniform way to DFP, e.g. inhibitory nociceptive pathways were less affected than excitatory ones. Esterase activities were heavily depressed and recovered with different time courses. The acute DFP action cannot be explained by a uniform intoxication of all spinal functions but probably emerges from a differential action on different interneuronal systems.

Acetylcholinesterase↗
PubMed1985

The effects of a new serotonin receptor antagonist (ketanserin) on lower urinary tract function in patients with prostatism.

Ten male patients with prostatism, median age 63 years (range 50 to 70 years) were given an intravenous injection of a new serotonin antagonist, ketanserin, at a dose of 10 mg., and were investigated urodynamically before and after injection. A statistically significant increase in maximum and mean flow rates and a statistically significant decrease in urethral pressure profile measurements was observed. Supine CO2 cystometry showed no significant decrease in volumes of first sensation and bladder capacity. No subjective side effects were registered, but we observed a statistically significant decrease in mean blood pressure of 6.5 mm. Hg (range 5 to 14 mm. Hg). The mechanism behind the beneficial effect of ketanserin on micturition in prostatism is not yet known, but the results could explain an alpha blocking effect of the drug.

Aged↗
PubMed1979

Effects on reflex bladder activity of chemical stimulation of small diameter afferents from skeletal muscle in the cat.

In anesthetized cats selective activation of fine muscle afferents of the hindlimb by KCl or bradykinin (Brad.) induced reflex changes in the urinary bladder. The nature of the reflex responses depended on the functional state of the bladder: they were excitatory when the bladder was quiescent and inhibitory during large, slow, rhythmic micturition contractions. Selective activation of large muscle primary afferents by succinylcholine was ineffective. All reflexes disappeared after cutting the sciatic or the pelvic nerves. Transection of the hypogastric nerves to the bladder had no effect.

Animals↗