Biomedical subjects

D C Fluck

Publications and source records attributed to D C Fluck.

6 recordsLinked to original sources

PubMed1978

Effect of submaximal isometric exercise on catecholamine, cAMP and lactate concentrations in the coronary circulation of man, following atropine and oxprenolol.

The effects of atropine and oxprenolol on changes occurring in total catecholamine, cyclic AMP (cAMP) and lactate concentrations in arterial and coronary sinus blood, during submaximal isometric exercise, were studied in 10 patients. Static one-third-maximal handgrip exercise, sustained for 5 minutes, did not produce an increase in either arterial or coronary sinus plasma catecholamine concentrations (measured at rest and during the last minute of exercise) and was not influenced by atropine and oxprenolol. Myocardial lactate production did not occur. Coronary sinus cAMP concentrations fell during isometric exercise from 11.53 +- 0.93 to 9.42 +/- 0.81 nmol/l (+/ SEM), and following autonomic blockade from 12.46 +/- 1.12 TO 9.6 +/- 0.87 nmol/l but rose on subsequent isometric exercise to 11.27 +/- 0.8 nmol/l (p less than 0.05). Although this latter increase could still be due to beta-adrenergic stimulation, the absence of any change in catecholamine concentrations in the presence of beta-blockade suggests that other factors may have been responsible.

Adult↗

PubMed1977

Effect of isometric exercise on catecholamines in the coronary circulation.

Arterial and coronary sinus blood levels of catecholamines, adenosine 3', 5'-cyclic monophosphate (c-AMP) and lactate were measured during isometric exercise in fourteen patients. In no patient did lactate production occur. Mean resting total catecholamine levels both arterial (0.53 +/- 0.07 ng/ml; 2.94 +/- 0.38 nmol/l) and coronary sinus (0.4 +/- 0.08 ng/ml; 2.22 +/- 0.44 nmol/l), did not change significantly on exercise. Coronary sinus c-AMP levels fell on exercise from 11.5 +/- 0.8 nmol/l (resting) to 9.9 +/- 0.8 nmol/l (exercise) (P less than 0.01) with an arterial-coronary sinus difference of 1.2 nmol/l (P less than 0.01) on exercise. Our findings suggest that isometric exercise does not normally result in excessive cardiac symphathetic activity.

Adult↗

PubMed1977

Smoking and catecholamine and c-AMP concentrations in the coronary circulation of man and the effect of oxprenolol.

Changes in catecholamine, c-AMP and lactate concentrations in the coronary circulation of man, during smoking, were studied in 12 patients. The heart rate increase from 63 +/- 2 beats/min (control) to 74 +/- 3 (smoking)(P less than 0.01), falling to 70 +/- 2 (10 min after smoking) (0.05 greater than P greater than 0.01), whilst coronary sinus c-AMP concentrations rose from 11 +/- 0.7 nmol/l (smoking) to 11.9 +/- 0.8 nmol/l (after smoking) (0.05 greater than P greater than 0.01; one tailed 't' test). There was no significant change in blood pressure, catecholamine or lactate concentrations. The study was repeated in eight of the patients following intravenous oxprenolol. Coronary sinus catecholamine concentrations increased from 4.1 +/- 0.7 nmol/l (control) to 5.5 +/- 1.1 nmol/l (after smoking) (0.05 greater than P greater than 0.01; one tailed 't' test), but heart rate and c-AMP concentrations remained unchanged, confirming that smoking-induced tachycardia is a result of a beta-adrenergic mechanism, at least part of which is due to a release of cardiac catecholamines. Arterial lactate concentrations increased only following oxprenolol from 0.74 +/- 0.07 mmol/l (control) to 0.83 +/- 0.09 mmol/l (smoking).

Adult↗

PubMed1977

Arterial and coronary sinus catecholamines and cyclic-AMP during dynamic supine exercise in patients with chest pain.

Arterial and coronary sinus catecholamine concentrations were measured during dynamic exercise in patients to assess the sympathetic response. Arterial concentrations increased from 1.77 nmol/1 (SEM = 0.53, n = 7) (control) to 2.95 nmol/1 (SEM = 0.65, n = 7) during exercise (0.05 greater than P greater than 0.01) and coronary sinus concentrations from 2.78 nmol/1 (SEM = 0.53, n = 7) (control) to 4.43 nmol/1 (SEM = 0.71, n = 7) (0.05 greater than P greater than 0.01). Resting, and exercise, arterial-coronary sinus differences in catecholamine concentrations were not statistically significant. In some patients, higher catecholamine concentrations occurred post-exercise than during exercise. The coronary sinus-arterial difference in catecholamine concentration during exercise was greatest in the one patient who developed angina pectoris. Cyclic-AMP concentrations were also measured, but these did not change significantly, consistent with the predominantly noradrenaline response to exercise.

Adult↗

PubMed1977

Autonomic blockade and coronary catecholamines and cyclic AMP in exercising man.

To assess in man the effects of autonomic blockade on the response of catecholamines in the coronary circulation to dynamic exercise, arterial and coronary sinus catecholamine concentrations were measured in six patients during supine cycling exercise, following atropine 1.8 mg and oxprenolol 0.2 mg/kg iv. Although arterial concentrations did not increase significantly, coronary sinus catecholamine concentrations increased from 2.54 +/- 0.59 nmol/1 at rest 4.44 +/- 1.3 nmol/1 during exercise (P less than 0.05; one-tailed test) and were associated with a small increase in heart rate and coronary sinus cyclic AMP concentrations from 9.4 +/- 0.7 nmol/1 (rest) to 11.6 +/- 1.1 nmol/1 (exercise) (0.05 greater than P greater than 0.01). Although autonomic blockade may have increased catecholamine release, this was not reflected in an increased efflux of catecholamines from the heart, because similar increases in coronary sinus catecholamine concentrations occurred in the absence of autonomic blockade.

Adult↗

PubMed1976

Evaluation of rapid atrial pacing in diagnosis of coronary artery disease. Evaluation of atrial pacing test.

Seventeen patients presenting with anginal-type pain were studied by bicycle exercise testing, rapid atrial pacing, and coronary angiography. Ten patients with angina and abnormal pacing tests at rates less than 180/minute were found to have significant coronary artery disease as demonstrated by coronary angiography. Seven patients with pacing-induced chest pain only at rates of 180 and above had normal coronary angiogram. This suggests that patients requiring rates of 180 or more to produce a positive atrial pacing test, following our protocol, do not usually have significant coronary artery disease though confirmation requires a larger study.

Adult↗