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Biomedical subjects

R Erspamer

Publications and source records attributed to R Erspamer.

9 recordsLinked to original sources
PubMed1983

Time limits of reversible cortical ischemia.

The duration and degree of reversible cortical ischemia was evaluated by monitoring the direct cortical response (DCR) and cortical blood flow as determined by a thermal diffusion flow probe (CBFp) in a small segment of cortex. Global ischemia was induced in 90 lightly anesthetized cats during recording. The thresholds for attenuation and abolition of the DCR were 23.7 +/- 6.9 (SD) and 8.7 +/- 3.4 ml/100 g/minute, respectively. With the abrupt drop of CBFp to 5 ml/100 g/minute or below, the DCR was obliterated in 2 to 6 minutes. Recovery of the DCR was likely to occur if it had been absent for only 10 minutes, but after 40 minutes without a DCR no animal recovered DCR, even though the animals were monitored for 6 hours. Correlation of CBFp with time of ischemia was done by analyzing the CBFp curve minute by minute and computing the mean CBFp during the ischemic insult. This was then compared to recovery of DCR. By plotting time (T) in minutes, CBFp in ml/100 g/minute, and recovery of DCR, T was identified for levels of CBFp when DCR would be unlikely to recover. The time limits of cortical ischemia are described for blood flows from 0 to 20 ml/100 g/minute. The physiological recovery of the cerebral cortex from ischemia is a function of the depth and duration of the ischemic episode.

Animals↗
PubMed1982

Cortical blood flow during craniotomy for aneurysms.

A previously described thermal diffusion flow probe was used to monitor cortical blood flow in over fifty craniotomies for treatment of aneurysms. Hypotension, retractor pressure, vascular manipulation, and temporary vessel occlusion can be seen to affect cortical blood flow. By monitoring cortical blood flow, anesthetic and surgical techniques may be altered to prevent ischemic complications. We have only limited experience with early operation and with craniotomy in the face of vasospasm. Monitoring cortical blood flow may eventually allow operations in these instances to be accomplished more safely.

Aged↗
PubMed1980

Dynamic quantitative assessment of cortical blood flow.

Dynamic real time quantitative assessment of cortical blood flow is feasible with a thermal diffusion flow probe. The probe consists of a Peltier stack that creates a thermal gradient. The thermal gradient has been calibrated against Xe133 clearance for fast flow. Rapid changes in flow induced with pharmacologic agents, changes in perfusion pressure, or vascular manipulation are readily apparent. This technique is useful for intraoperative assessment of cortical blood flow and may prove useful in postoperative monitoring.

Animals↗
PubMed1975

Dopaminergic mechanisms of opiate actions in brain.

We have studied the interactions between morphine and a dopamine-blocking agent (haloperidol) and a dopamine precursor, L-3,4-dihydroxyphenylalanine (L-dopa). We found that haloperidol potentiated morphine-induced analgesia and enhanced morphine tolerance. Morphine-tolerant mice exhibited enhanced sensitivity to the locomotor excitatory actions of L-dopa. We propose that morphine exerts some of its central nervous actions by first interfering with dopamine-mediated synaptic transmission and then initiating compensatory changes that superficially resemble denervation supersensitivity. These compensatory changes may underlie the excitatory actions of morphine.

Analgesics↗
PubMedDate not supplied

Genetically determined differences in the effects of morphine on mice.

We have compared a variety of well known behavioral actions of morphine across four strains of laboratroy mice. Thes measures included locomotor activation, analgesia, tolerance, dependence and drug-seeking. We found that analgesia and drug-seeking did not vary greatly among strains, although some statistically significant differences were found. The interstrain rank ordering for locomotor activity, tolerance and dependence was different for each of these measures. This suggests that each of these effects of morphine may depend upon separate mechanisms, perhaps with each under independent genetic control. Other experiments were carried out to determine whether or not there were differences in the in vivo brain uptake of an opiate or the in vitro binding of naloxone to 'stereospecific receptors'. No significant interstrain differences could be found.

Analgesia↗
PubMedDate not supplied

Cortical blood flow: thermal diffusion vs isotope clearance.

A thermal diffusion flow probe incorporating a Peltier stack has been found to give a quantitative dynamic assessment of cortical blood flow in both the laboratory and clinical settings. Further calibration characteristics of the probe were evaluated by correlation with the fast component of Xe133 clearance in cats. The correlation has some linear characteristics but is better defined by the equation: CBFp = phi(1/delta V - 1/delta Vo) Where CBFp is flow in ml/100 g/min, delta V is the voltage difference of the thermocouples, and delta Vo is the voltage difference of the thermocouples with no flow, which was 342.8 +/- 12.9 microv. Phi describes the characteristics of the probe and was determined to be 52,431.2 +/- 4796.3. The average deviation of the calculated curve from the experimental data points was +/- 6.3. The calculated phi differed markedly from the mean when Xe133 fast component flows were less than 35 ml/100 g/min. This is evidence that CBF as measured by Xe133 clearance analyzed by the bicompartmental technique loses accuracy at lower flows. The thermal diffusion flow probe is a good device for evaluation of flow in acute ischemia models since it can delineate abrupt flow variations. Theoretically the flow probe can accurately measure flow at ischemic levels.

Animals↗
PubMedDate not supplied

Cortical ischemia: effect upon direct cortical response.

Correlation of cortical blood flow as measured by a thermal diffusion flow probe (CBFp) with the direct cortical response (DCR) was studied in 48 lightly anesthetized cats with global ischemia. Thresholds for attenuation and loss of DCR were 21.3 +/- 4.7 and 8.7 and 3.4 ml/100 g/min respectively. In abrupt ischemia, CBFp of 0-3 ml/100 g/min produced absence of DCR in 6 min or less; however, at CBFp of 5-10 ml/100 g/min, the time to obliteration of DCR varied from 5 to 180 min. DCR was unlikely to recover after 13 min of 0-2 ml/100 g/min and after 35 min of 4-5 ml/100 g/min. At higher flows, DCR could recover over 60 min or more of ischemia. With gradual production of ischemia, flows less than 20 ml/100 g/min for over 60 min had a detrimental effect upon recovery of DCR if DCR was lost for 7.5 min or more. Some evidence that implied adaptability of the cortex to ischemia was found.

Animals↗