Cardiovascular, endocrine, and receptor measures as related to sex and menstrual cycle phase.

OBJECTIVE: The present study was undertaken to elucidate possible mechanisms underlying sex differences in cardiovascular measures or reactivity to challenge. Because there is vastly diverging literature on the issue, we tried to control for endocrine and psychological factors, which might contribute to some of the apparent discrepancies. METHODS: Blood pressure, heart rate, adrenaline, and noradrenaline in women (N = 24) and men (N = 14) were examined during baseline and challenge (Stroop Test and Cold Face Test). Adrenoceptor density on lymphocytes (beta 2) and platelets (alpha 2) were determined to examine possible sex differences in underlying cardiovascular mechanisms. Gender effects were controlled by assessing gender role orientation and task appraisal. Women were tested during either the follicular (N = 12) or the luteal (N = 12) phase of the menstrual cycle (verified by estradiol, progesterone, and luteinizing hormone). RESULTS: Follicular and luteal phase women did not differ in any parameter except progesterone. We observed sex-related differences in absolute levels of physiological parameters, the male group having higher systolic blood pressure levels, higher adrenaline plasma concentrations, and significantly more alpha 2-adrenergic receptors. Both challenges elicited pronounced cardiovascular and endocrine responses. Men and women did not differ in response magnitude, in task appraisal, or gender role orientation. CONCLUSIONS: The assumption that female sex hormones reduce reactivity to challenge is not supported by our data. The frequently reported male/female differences in reactivity may be caused by an interaction of gender and task characteristics.

[The hearing organ: active sound amplifier and highly sensitive measuring system]. / Das Hörorgan: Aktiver Schallverstärker und hochempfindliches Messsystem.

The present paper provides a brief review on topical issues of auditory physiology. Recent data on transduction mechanism and adaptation in hair cells as well as on the possible role of outer hair cells in amplifying basilar membrane motion are presented. Strategies of present physiological research in dealing with sensorineural deafness are discussed.

Working with new technologies: hormone excretion as an indicator for sustained arousal. A pilot study.

Effects of working with new technologies (visual display units) on hormone levels were investigated in a pilot study. The relationship between subjective strain and hormone levels was also assessed. Twenty subjects participated in the study reported here, which is a part of a comprehensive longitudinal study, in which 279 employees participated. Measurements were taken two months before the new technology was installed (baseline: work with conventional technology), during the implementation phase of the new technology, and at a 12-month interval. Fourteen complete data sets were analysed. The introduction of new technologies was accompanied by enhanced levels of catecholamines (epinephrine and norepinephrine). Levels also remained high one year after the implementation. Similar values were found on work days and rest days. Cortisol changes were less evident; excretion tended to increase after the implementation had been completed. The relationship was weak between hormone levels and subjective strain measurements. The results indicate that working with new technologies was accompanied by enhanced physiological arousal of the employee. Reactivity was related more to a particular occupational setting than to scales of subjective assessment.

[Personal variables and their effects on physiologic stress reactions]. / Personale Variable in ihren Auswirkungen auf die physiologischen Beanspruchungsreaktionen.

In 24 male medical students hormonal, cardiovascular and state of mood data were collected on the day of an oral examination as compared to a control day. Analyses included 24-hour-noradrenaline-, adrenaline- and cortisol-excretion, blood levels of free testosterone, heart rate and blood pressure readings and state of mood ratings (Nitsch). Furthermore subdimensions of the type A construct, as included in the need-for-control questionnaire (Siegrist), were determined. Four subgroups were established according to total amount and stress reactivity of noradrenaline (NA) excretion. Further analysis showed that this line of separation held for the remaining hormones as well, thus revealing rather homogenous group- inherent hormonal patterns. However, in both groups with low hormonal stress reactivity cardiovascular reactivity was higher than in the groups with a pronounced hormonal stress response. Blood pressure rose highest and recovered slowest in the group, who had the highest NA and cortisol excretion on control day and highest allover cortisol excretion. This group rated high in the Siegrist subdimension "task-involvement" (inability to withdraw), the difference to the remaining groups being statistically significant. Neither the amount of hormonal nor that of cardiovascular reactivity were related to the state of mood ratings.

A second order model of the optic generator potential and its relation to Stevens' power function.

The component PIII of the electroretinogram representing the optic generator potential was recorded after stimulation with short stimuli with different light intensity. It is shown that the impulse response function of a linear second order model with intensity-dependent coefficients can be well fit to the recordings. Two of its parameters, after logarithmic transformations, are linearly dependent on the luminance while the third parameter varies only within a small interval. It is therefore possible to describe the relation between PIII and luminance in a linearized second order model. Furthermore, both the type of the function relating the gain of the model to the luminance and its exponent are nearly identical with the psychophysic function relating luminance to subjective brightness. Further physiological implications are also considered.

[Aspartate transfer across the blood-retina barrier (author's transl)]. / Permeabilität der Blut-Retina-Schranke für Asparaginsäure.

Permeability of the blood-brain barrier is restricted with respect to amino acids involved in neurotransmission. This finding is well-documented in the case of gamma-amino-butyric acid (GABA) and glycine. Aspartic acid, which is also considered to be a transmitter, equally does not cross the blood-brain barrier in the rat with ease. This amino acid is also thought to be a transmitter in the retina. In order to examine the permeability of the blood-retina barrier with respect to aspartic acid, and investigation was undertaken of the effect of asparate on the light-induced sum potential of the retina in the isolated, perfused cat eyeball, a preparation which guarantees intact retinal circulation. The findings were compared with findings in the isolated retina where the substance was brought into direct contact with the retinal neurons. It was found that aspartate crossed the vascular barrier only to a limited extent and with delay. These results support the hypothesis that aspartic acid is involved in the retinal information processing.

Effect of azide on the ERG of the isolated mammalian retina.

Azide, which is known to affect the pigment epithelium strongly may be assumed to cause damage to the receptors, which are functionally connected to the pigment epithelium. To check this hypothesis the effect of azide on the ERG was investigated. An isolated retina preparation was used as in this preparation the P III component, which contains considerable receptor contribution, can be isolated. In 2 series of experiments the effects of azide on the P III and the complete ERG were investigated. Depending on the concentration azide was shown to abolish the b-wave, to cause delay and amplitude diminution of the P III and enhance a positive component in the off-effect. A number of plausible sites of origin of these azide effects on the ERG changes are discussed.