Effect of continuous darkness on diurnal rhythms in small vesicles in sympathetic nerve endings of the mouse pineal-quantitative electron microscopic observations

Quantitative electron microscopic studies on the effect of continuous darkness on the diurnal rhythm of small vesicles in sympathetic nerve endings of the mouse pineal demonstrate that the numerical change of type 1 granulated vesicles, predominant small granulated vesicles, and non-granulated elliptical vesicles seen during the first half of the dark period under diurnal lighting conditions may persist for at least 14 days under continuous darkness. Furthermore, it is found that the alteration in the number of type 1 granulated vesicles and the total vesicle density observed during the light period under diurnal lighting conditions may be lost in mice kept in continuous darkness for 7 days. This result indicates that the type 1 granulated vesicles may be composed of two different populations of vesicles, i.e., granulated vesicles of population 1 and 2, and that the diurnal rhythm in the number of the granulated vesicles of population 1 may be abolished, while that of the granulated vesicles of population 2 may be maintained, under continuous darkness. The diurnal variation in the number of the type 2 granulated vesicles, which constitute a small population of small granulated vesicles, may persist in darkness. Thus, the diurnal rhythm in the number of small granulated vesicles in sympathetic nerve endings of the mouse pineal may be controlled by two different mechanisms, exogenous and endogenous.

Further studies on diurnal changes in small vesicles in sympathetic nerve endings in the mouse pineal and the effects of continuous light on the vesicles--quantitative electron microscopic observations

Diurnal variations in the number of various types of small granulated and non-granulated vesicles as well as effects of continuous light on the vesicles in sympathetic nerve endings of the mouse pineal were investigated using quantitative electron microscopic techniques. Small granulated vesicles, 40 to 80 nm in diameter, were classified into two categories, type 1 or type 2, according to the size of the granule. Small non-granulated vesicles were also divided into two categories, i.e., spherical and elliptical. Non-granulated vesicles with the long diameter more than twice the shorter one (ranging from 50 to 90 nm in long diameter) were referred to as elliptical vesicles and the other (ranging from 40 to 80 nm in diameter) as spherical vesicles. The number of small vesicles, except for the non-granulated spherical vesicles, varied diurnally in relation to the daily photoperiod. The total vesicle density also exhibited diurnal changes. On the basis of these observations, possible relationships between small vesicles and noradrenaline or serotonin were discussed. Both the diurnal variation in small vesicles and that in the total vesicle density were completely abolished by continuous lighting. Continuous light exposure for various periods until 35 days provoked no apparent changes in small vesicles, except the type 2 granulated vesicles, which were increased in number in response to continuous lighting for about 1 to 3 days.

Diurnal variation in large granulated vesicles in sympathetic nerve fibers of the mouse pineal--quantitative electron micrsocopic observations

Quantitative electron microscopic studies of the sympathetic nerve fibers of the mouse pineal demonstrated a marked diurnal rhythm in the number of the large granulated vesicles of 80 to 150 nm diameter. The number of these vesicles showed its minimum at the middle and the end of the dark period and its maximum at the end of the light period, respectively. The large non-granulated spherical and elliptical vesicles were almost constant in number throughout the day.

Volatile metabolites of halothane in the rabbit

To date, carbon dioxide is the only volatile metabolite that has been identified to result from the biotransformation of halothane. This study was undertaken to determine whether other volatile metabolites might be formed. Expiratory gas from four rabbits given halothane by inhalation and from three rabbits into which the halothane was injected intraperitoneally was analyzed by gas chromatography. Qualitative analysis of the metabolites was made by injecting 50-70 microliter of the expired halothane condensed in an ultralow-temperature device (-80 C) attached to the mass spectrometer. Gas chromatography revealed two volatile metabolites between the air peak and the halothane peak. They were identified by mass spectra to be CF2:CHCl and CF2CH2Cl. These volatile metabolites appeared immediately after the beginning of anesthesia. The present investigation suggests the possible existence of a previously unknown metabolic pathway of defluorination and debromination occurring in the early stage of halothane biotransformation. These volatile metabolites may be toxic, highly reactive intermediates that undergo further biotransformation.

Management of anaesthesia in an infant with an anomalous lung arising from the oesophagus

The anaesthetic management of a 19-month-old male infant undergoing pneumonectomy for a rare congenital anomaly is discussed. The trachea communicated solely with the left lung and there was an abnormal communication between the oesophagus and the right main-stem bronchus. Gross infection of the right lung was present. Our experience suggests that the following points are of importance: (1) There is a substantial risk in intubating deeply into the trachea because of the possible existence of a bronchial pouch at the bifurcation. (2) Since the stomach may be full of pus, aspiration of pus before induction of anaesthesia and before extubation is essential. (3) Pneumonectomy with the patient in the supine position is advised.

Functional relationships between sympathetic nerves and pinealocytes in the mouse pineal: quantitative electron microscopic observations

Quantitative electron microscopic observations on the pineal gland of the mouse were made in order to demonstrate ultrastructural changes in response to various conditions of illumination in sympathetic nerve fibers as well as in pinealocytes and, thus, to establish some morphological correlates of a functional relationship between sympathetic nerves and pinealocytes. The diurnal change in the number of the small granulated vesicles (60 nm in diameter) in sympathetic nerve fibers of the mouse pineal is similar to that of the noradrenaline content in the rat pineal; increasing at night to reach the maximum level at the beginning of the light period of the day. A marked decrease of the small granulated vesicles seen after the onset of darkness may be correlated with a release of noradrenaline from the nerve fibers. Since the diurnal change in the number of the granulated vesicles (100 nm in diameter) and the glycogen content in the mouse pinealocytes closely resemble each other, the diurnal variation in the number of the granulated vesicles and the amount of glycogen may be influenced by a diurnal rhythm in the release of noradrenaline. The number of the granulated vesicles and the glycogen content in the pinealocytes show another striking similarity in that their remarkable increase is induced by continuous light for relatively short periods. It is speculated that light suppresses the release of noradrenaline from the nerve fibers and, thus, causes an increase of the glycogen content as well as the number of the granulated vesicles in the pinealocytes.