Total Metabolism of the Mouse After Pseudoparturition and Parturition

Many investigations have been made on the metabolic exchanges during pregnancy, both in women and in lower animals. The most important of these have recently been reviewed by Newton (1952). Although all the problems examined remain, to a greater or less extent, incompletely answered, the most notoriously refractory problems of metabolism in pregnancy are those of energy and water exchange. While it is generally accepted that the energy expenditure of the pregnant organism increases during pregnancy, is the increase due to the event of pregnancy or is it simply a reflexion of increasing tissue mass (that is, roughly, body weight) and changes in food intake (that is, roughly, specific dynamic action)? Again, does the pregnant organism normally retain water in excess of that required for the formation of tissue and fluids of the conceptus, and of new maternal tissue in the uterus, mammary glands and elsewhere?The present investigation was designed to contribute something towards the solution of these problems, by measurement, in the rat, of the total energy exchange over prolonged periods, as opposed to short-period basal studies, and by simultaneous measurement of the total water exchange with direct measurement of the water balance.Earlier studies on the energy expenditure of pregnancy have been confined, with one or two exceptions, to short-period measurements of basal metabolism from time to time throughout pregnancy. Only in Dewar's (1953) work on the mouse have data been available to examine the total energy metabolism during pregnancy. Neither, until Dewar's (1953) work, has there been any direct estimation of water balance during pregnancy. The belief that water retention is a general phenomenon of pregnancy has been inferred exclusively from indirect evidence, the main lines of which have been reviewed by Chesley (1944). Dewar (1953) was, however, primarily interested in the part played by the placenta in the control of pregnancy, so all his results, including

Section: Failed Pregnanciesmentioning

confidence: 71%

Section: Failed Pregnanciesmentioning

confidence: 83%

mentioning

confidence: 99%

See 1 more Smart Citation

The total energy and water metabolism during pregnancy in the rat

Morrison¹

1956

“…Recently, Dewar & Newton (1948 a) and Dewar (1953) have made successive 24 hr total metabolism studies on mice, with particular regard to pseudoparturition, and Blaxter, Graham & Rook (1953) on farm animals in which the classical basal conditions have been abandoned and the total respiratory and other metabolic exchanges under normal living conditions have been measured. In this way a normal picture of the energy exchanges of the animal has been obtained, each day's run representing a set of directly comparable data on the same animal.…”

Section: S D Morrisonmentioning

confidence: 99%

The total energy metabolism of non‐pregnant rats

Morrison¹

1955

Much information has accumulated over the years on the so-called 'basal' metabolism of many mammalian species. Such information is of great value for some purposes, notably for the comparison of the effects on energy metabolism of various pharmacological and hormonal agents. There are, however, objections to the use of 'basal' determinations as a measure of the normal energy economy of the organism. 'Basal' metabolism, better described as the resting, post-absorptive metabolism, can be determined only over relatively short periods, not more than 1 hr and usually not more than 10 or 15 min; the extrapolation of measurements of such short duration to a period of 24 hr can introduce errors of considerable magnitude. Also, it has been pointed out by and by Forbes, that the apparent effect of specific dynamic action (S.D.A.) in the post-absorptive animal is different to that in the normally feeding animal. The diurnal variations in energy expenditure, pointed out by many workers (e.g. , cannot be taken into account by means of single 'basal' determinations; repeated short-period determinations at intervals throughout the day and night, on the other hand, disturb the normal pattern of behaviour of the animal.In the case of small animals a more serious difficulty in the evaluation of the significance of 'basal' energy arises since the post-absorptive animal is difficult to distinguish from the frankly starving animal; in addition, the true resting state is almost impossible to achieve in small animals for more than a few minutes at a time. Brody, Riggs, Kaufman & Herring (1938) have shown that, in the post-absorptive rat, lactation is severely depressed, and within 8 hr of the last feed completely fails. Such a drastic effect on a normal function at the beginning of what is usually regarded as the post-absorptive period is a strong indication that, in the rat, the post-absorptive state cannot be regarded as physiological.

“…An increased water loss sometimes occurs post partum. Recently Dewar (1953) has demonstrated directly a post partum loss of water in the mouse, corresponding in time and magnitude to the post partum loss of body weight.…”

Section: Studies Edinburghmentioning

confidence: 99%

Proceedings of the Physiological Society

1954

Water-metering device which simultaneously operates and measures the output of a blood pump. By I. DE BURGH DALY.Institute of Anrimal Physiology, Babraham, CambridgeA low-output blood pump of small blood capacity was required for the control and measurement of arterial volume inflow.Blood pump. The sectional elevation (inset A) shows the Perspex body of the pump into which are inserted three tapered (10) spigots carrying the inlet (a) and outlet (b) valves and the water chamber (c) separated from the blood chamber (d) by the rubber diaphragm (e). Large circular heads (f) with fluted edges facilitate insertion and withdrawal of the spigots. The valves are strips of thin rubber sheet fixed lightly over the inlet and outlet orifices (as shown) or are conventional flattened rubber tubing. The volume of the pump chamber, inlet and outlet channels is 2l5 ml. Pulsatile pressure changes in the water chamber are produced by connecting it alternately with a water-pressure head and with atmospheric pressure. This is done by rotary or electromagnetically operated valves.Rotary valve. The logitudinal (B) and cross (C) sections show a spindle (g) which under operating conditions rotates in the body (h). Communication between parts 1 and 2 and between 3 and 4 in the body takes place alternately by means of two 1200 slots cut in the spindle 180°out of phase. Port 1 is connected to a pressure head of water; ports 2 and 3 are both connected to the inlet (i) of the pump-water chamber, and port 4 to a volume-flow recorder operating at atmospheric pressure. Thus ports 2 and 3 can be regarded as a single port alternately communicating with port 1 and port 4. Rubberpressure tubing or polythene tubing is used for the connexions. When ports 1 and 2 communicate the water flowing into the water chamber (c) displaces an equivalent amount of blood through the blood-pump output valve (b). When ports 3 and 4 communicate the elastic recoil of the rubber diaphragm displaces the water through port 4 and at the same time draws in an equivalent amount of blood through the input valve (a). Thus the volume inflows and outflows of the rotary-valve assembly and the blood pump should be similar.The 'systolic' output of the blood pump mainly depends upon the compliance of the membrane and the difference between the pressures in the water Hg and the pump-output pressures varied from 0 to 126 mm Hg, whereas in Expts. IV and V the output pressures were approximately zero and the waterinflow pressures varied from 0 to 150 mm Hg. In Expt. III the water flow was intermittently controlled 51 times per minute by electromagnetically operated clamps on the rubber-tubing connexions. In one series of observations the water-inflow pressure was 100 mm Hg and the pump output pressures 20 to 100 mm Hg; in the other the corresponding values were 200 mm Hg and 25-175 mm Hg. The outputs of the rotary valve tend to exceed somewhat those of the blood pump especially at the lower outputs. This was in part due to incompetence of the valves at the lower pump outputs, and in...