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Biomedical subjects

B J Chapman

Publications and source records attributed to B J Chapman.

At least 37 records · Page 2Linked to original sources
PubMed1982

The effects of thermal injury on gastrointestinal motor activity in the rat.

Gastrointestinal motor function was studied in conscious rats. The gastric emptying time, small intestinal motility and the colonic transit time were measured. A burn injury, covering about 15 per cent of the body surface area was applied to experimental animals; control animals received a mock burn. Burn injury caused a marked inhibition of gastrointestinal motility. This inhibition was significantly improved by a continuous saline infusion, but saline infusion alone had no effect on the gastrointestinal propulsive motility of normal rats.

Animals↗
PubMed1982

Renal blood-flow changes during renal nerve stimulation in rats treated with alpha-adrenergic and dopaminergic blockers.

1. Blood flow through the inner cortex and outer medulla of the rat kidney was measured by the hydrogen wash-out technique. 2. Renal nerve stimulation caused vasoconstriction in both cortex and medulla. This constriction was abolished or reduced by phenoxybenzamine (9 mumole/kg I.V.), phentolamine (100 n-mole/kg) or prazosin (1.5 mumole/kg). 3. After prazosin (6 mumole/kg I.V.), renal nerve stimulation caused small but significant renal cortical vasodilatation. This vasodilatation was reversed by sulpiride (0.7 mumole kg-1 min-1), but was unaffected by propranolol (10 mumole/kg) or atropine (4.3 mumole/kg). 4. These results indicate the existence of dopaminergic vasodilator nerves to the renal cortex of the rat.

Adrenergic alpha-Antagonists↗
PubMed1981

Impedance cardiography: non-invasive cardiac output measurement after burn injury.

The election of blood from the heart produces changes in transthoracic impedance. It has been proposed that the cardiac output may be determined from these changes. The cardiac output was measured by impedance cardiography and by the thermal dilution method before and after full thickness burn injury to the skin of the anaesthetized rat. The values obtained by the impedance method showed a good correlation with simultaneous thermal dilution cardiac output measurements (r=+0.67 pre-burn, and +0.76 post-burn). Impedance cardiography confirmed the early post-burn reduction in cardiac output reported by other workers using invasive techniques. Good agreement between the two methods was also obtained when the cardiac output of burn injured animals was altered by fluid infusion. This non-invasive technique of cardiac output monitoring may therefore have an important place in the investigation of cardiac function after trauma and burn injury.

Animals↗
PubMed1980

Half-life of angiotensin II in the conscious and barbiturate-anaesthetized rat.

The half-life (T 1/2) of angiotensin II was measured in rats with chronic indwelling catheters. In conscious animals T 1/2 was 14.8 +/- 2.5 s; during anaesthesia T 1/2 increased by 60%. Anaesthesia decreased the control arterial pressure, but did not alter the sensitivity to injected angiotensin II. The causes and consequences of this change in angiotensin catabolism are discussed.

Anesthesia, General↗
PubMed1980

The actions of dopamine and of sulpiride on regional blood flows in the rat kidney.

1. Blood flow was measured in the renal cortex and medulla of anaesthetized rats by the hydrogen washout method. The effects of dopamine infusion were measured. 2. Low doses of dopamine (20 and 65 n-mole.kg-1.min-1) caused only small increases in renal blood flow, and a higher dose (200 n-mole.kg-1.min-1) caused vasoconstriction. After alpha-blockade with phenoxybenzamine (9 mumole.kg-1), all doses of dopamine caused vasodilatation in the cortex and medulla of the kidney. 3. This dopamine-induced renal vasodilatation was almost abolished by sulpiride (0.7 mumole.kg-1.min-1), but was only slightly attenuated by propranolol (10 mumole.kg-1). 4. Sulpiride did not significantly alter the renal blood flow responses to noradrenaline or isoprenaline, or the blood pressure responses to histamine, acetylcholine, 5HT, noradrenaline and isoprenaline. 5. In normal rats, infusion of sulpiride generally caused a reduction in renal cortical blood flow. This response showed a positive correlation with the initial blood pressure. 6. It is concluded that there are specific dopamine receptors in the renal vasculature of the rat, and that dopamine may play a role in the normal control of renal blood flow.

Animals↗
PubMed1978

The half-lives of angiotensin II, angiotensin II-amide, angiotensin III, Sar1-Ala8-angiotensin II and renin in the circulatory system of the rat.

1. Methods are described for estimating the half-life of angiotensin analogues and renin in the rat, from the time course of the blood pressure changes they evoke. 2. The following half-life values were measured: angiotensin II, 16 +/- 1 sec; angiotensin III, 14 +/- 1 sec; angiotensin II-amide, 15 +/- 1 sec; Sar1-Ala8-angiotensin II, 6.4 +/- 0.6 min; renin, 3.0 +/- 0.4 min. The distribution volume of angiotensin was found to be 18 ml./kg body wt. 3. It is inferred that the Asp1 residue does not reduce the rate of angiotensin II catabolism, but that substitution of this residue by sarcosine may inhibit catabolism while substitution by asparagine has no effect. 4. Five experimental criteria were identified which indicate that these methods give reliable estimates of the half-life. It is suggested that these results are more accurate than most previous half-life estimates. 5 When tachyphylaxis to angiotensin II-amide occurs, the pressor activity of the plasma is not reduced.

Angiotensin Amide↗