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Biomedical subjects

W H Cottle

Publications and source records attributed to W H Cottle.

14 recordsLinked to original sources
PubMed1985

An improved glyoxylic acid technique for the histochemical localization of catecholamines in brown adipose tissue.

A glyoxylic acid method using cryostat sections to demonstrate catecholaminergic fibres of the central nervous system was modified to show the extent of the adrenergic innervation in rat brown adipose tissue. It revealed prominent interlacing fluorescent parenchymal fibres surrounding individual adipocytes. The density of this network of fine fibres was not evident using earlier techniques. The new method also confirmed the dense networks of adrenergic fibres associated with arterial vessels. Its specificity was verified by simultaneously performing radioenzymatic determinations of tissue catecholamine levels and histochemical studies of brown adipose tissue from normal and sympathectomized rats. Chemical sympathectomy with 6-hydroxydopamine resulted in a pronounced decrease in brown adipose tissue and heart catecholamine (noradrenalin and dopamine) levels. Significantly, in brown adipose tissue of sympathectomized animals no fluorescence could be detected in terminal nerves of either the parenchyma or those of vascular smooth muscles. Nevertheless, some intense fluorescence was seen in axon bundles. The findings suggest that catecholamines of the parenchymal innervation form a larger proportion of the total catecholamine content of brown adipose tissue than was previously believed, provide stronger support for direct control of the function of multilocular adipocytes, and also confirm unpublished data reporting considerable dopamine content in brown adipose tissue.

Adipose Tissue, Brown↗
PubMed1978

Hypoxia, smoking history, and exercise.

Six nonsmokers and six cigarette smokers, 22-34 years old, performed bicycle work (53% sea level VO2 max) for 30 min in an altitude chamber under four conditions: SL, simulated sea level (PIO2 = 159 torr, PB = 523 torr) with 0.5% HbCO; SLCO, simulated sea level with 4.2% HbCO; and ACO, altitude with 4.2% HbCO. During work at altitude, heart rate (HR), minute ventilation and tidal volume increased and diastolic blood pressures decreased relative to SL. Cardiac output (Qc), stroke volume (SV), and arterial-mixed venous oxygen difference (a--vO2) were similar in smokers and nonsmokers at SL, SLCO, and A. At ACO, nonsmokers increased Qc and SV and decreased a--vO2, but these were not influenced in the smokers. Smokers showed a graded increase in HR when exposed to work in SLCO, A, and ACO. Their lower finger temperatures during A and ACO suggested vasoconstriction in the extremities. Cigarette smokers may be partially adapted to hypoxia.

Adult↗
PubMed1971

Influence of ambient temperature on the thermoregulatory responses to 5-hydroxytryptamine, noradrenaline and acetylcholine injected into the lateral cerebral ventricles of sheep, goats and rabbits.

1. The influences of ambient temperature (T(a)) on the thermoregulatory effector activities and the body temperature (T(b)) of intraventricular injections into the sheep, goat and rabbit of 5-hydroxytryptamine (5-HT), noradrenaline (NA), acetylcholine (ACh), carbachol and eserine, have been interpreted in terms of a simple neuronal model of the pathways between thermosensors and thermoregulatory effectors.2. In all three species 5-HT in minimal doses caused a rise in respiratory frequency (RF) and a fall in T(b) at high T(a), and a reduction in EMG activity and a fall in T(b) at low T(a). These effects could be interpreted as those of an excitatory transmitter acting on the warm receptor-heat loss pathway.3. In all three species NA caused a reduction in RF and a rise in T(b) at high T(a), and a reduction in EMG activity and a fall in T(b) at low T(a). These effects are interpreted as those of an inhibitory transmitter acting both on the warm sensor-heat loss pathways and on the cold sensor-heat production pathway.4. The effects of ACh and the cholinomimetic substances carbachol and eserine are complex and more difficult to interpret. In small doses the effects on the sheep and goat are those of an excitatory transmitter on the cold sensor-heat production pathway. There was an increase in EMG activity and a rise in T(b) at low T(a), and a reduction in RF and a rise in T(b) at high T(a). At higher dose levels in the goat and at all dose levels in the rabbit these substances had the reverse effects which are attributed to a synaptic block due to the excess of the excitatory substance.5. The effects of ambient temperature and injected substances upon ear temperature are consistent with the predictions of the model if it is assumed (a) that at high and low ambient temperatures direct thermal effects on ear vessels dominate those of the sympathetic innervation, and (b) that the warm sensor influence is to lower peripheral vasomotor tone, and the cold sensor influence is to increase it.6. The conclusion reached is that when consideration is given to species differences in the thermoneutral ambient temperature and to the possibility that excitatory substances have reversed effects at high dose levels, the effects of 5-HT, NA and ACh in the control of body temperature are very similar in the sheep, goat and rabbit: 5-HT is excitatory on the heat loss pathway, ACh is excitatory on the heat production pathway and NA has an inhibitory influence on both pathways.

Acetylcholine↗