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Biomedical subjects

L H Hartley

Publications and source records attributed to L H Hartley.

At least 55 records · Page 3Linked to original sources
PubMed1984

Enhanced blood pressure responses to loud noise in offspring of monkeys with high blood pressure.

Sixteen unanesthetized immature Macaca fascicularis monkeys, 18-43 months of age, were tested for mean arterial blood pressure (MBP) and heart rate (HR) responses to 30 minutes of continuous broadband noise (95 dB). Eight animals (OH group) were offspring of monkeys with high blood pressure (parents' MBP = 115.5 +/- 1.0 (SEM) mmHg), and eight (OC group) were offspring of control animals with normal blood pressure (parents' MBP = 96.6 +/- 1.7 mmHg). Resting MBP during a 17-24 hour period prior to the experiment in the OH group was 100.6 +/- 1.9 mmHg, significantly higher (p less than 0.05) than the MBP of the OC group (94.3 +/- 2.2 mmHg.) Immediately prior to noise exposure, MBP in the OH group was stable for 30 minutes, at 104 +/- 3 mmHg. During noise exposure, MBP increased significantly to 108 +/- 4 mmHg. In the OC group, MBP during the 30 min baseline interval was 95 +/- 2 mmHg, and during noise exposure was not significantly changed at 94 +/- 3 mmHg. Heart rate decreased significantly during noise in the OC group and did not change in the OH group. The results indicate that the offspring of monkeys with high blood pressure had higher resting MBP than control animals and showed significant MBP increases in response to loud noise. Control animals showed no change in MBP and decreases in HR in response to noise.

Animals↗
PubMed1984

Antisera to human renin normalize renin-dependent hypertension in the monkey: therapeutic implications.

Polyclonal antisera raised against pure human renin normalize renin-dependent blood pressure elevation in the monkey (M. fascicularis). In vitro, comparable inhibition of either human or monkey plasma renin by the antisera was demonstrated. In vivo, intravenous infusion of 2 ml of antisera did not change mean arterial pressure of salt-repleted monkeys, however, its administration to salt-depleted monkeys with elevated plasma renin activity lowered mean arterial pressure 10 Torr. A 25 Torr rise in mean arterial pressure and increase in plasma renin activity occurred promptly after inflation of a suprarenal aortic cuff in conscious uninephrectomized monkeys. Administration of 2 ml of antisera to these monkeys normalized mean pressure, which was reduced by an additional 10 Torr if the animals were previously salt-depleted. Maximal hypotension occurred within 1 hour and was sustained for approximately 10 hours. Because of the differing specificities of polyclonal antisera, sera raised in two laboratories against human renin purified from different sources were employed. Identical results were obtained. This is the first demonstration of the use of antisera to inhibit endogenous renin activity in primates and predicts the in vivo efficacy of renin antisera as experimental, diagnostic and therapeutic agents.

Animals↗
PubMed1984

Blood pressure values in Macaca fascicularis.

Normal data are presented for blood pressure values of adult Macaca fascicularis. The mean arterial pressure (direct) was 99 +/- 9.8 mmHg (mean +/- standard deviation) and was not correlated with sex, age, or weight. Normative data are presented that suggest that this species has a range of values similar to that observed in other primate species including man.

Age Factors↗
PubMed1983

Epinephrine mediated increases in plasma cholesterol.

The effect of physiological elevations of plasma epinephrine levels on plasma cholesterol levels was studied in ten cynomolgus monkeys. Epinephrine was increased 5 days/week for 6 hr/day. After 2 weeks, the cholesterol levels increased on the average of 15 mg% (p less than 0.01).

Animals↗
PubMed1980

Evidence for emotionally-induced coronary arterial spasm in patients with angina pectoris.

Twelve executives with typical angina pectoris, given a 12-minute quiz, designed to be psychologically stressful, responded with ST depressions of greater than or equal to 1.0 mm. Each of these patients was given an exercise tolerance test on an upright bicycle to induce an amount of ST depression equivalent to that observed during the quiz. A statistical analysis was made of the products of the heart rate and the systolic blood pressure (rate-pressure product), at the onset of equivalent ST depression on both tests. At the maximal ST depression during the quiz, the mean rate-pressure product was 181 +/- 64 (SD) X 10(2), and at an equivalent ST depression during exercise it was 225 +/- 54 X 10(2); the mean difference was 44 +/- 40 X 10(2). Inasmuch as the rate-pressure product is an index of myocardial oxygen consumption, the differences in rate-pressure product suggest that myocardial ischaemia occurred at a lower myocardial oxygen consumption during emotional stress than during exercise. If equivalent degrees of ST depression during exercise and the quiz are indicative of equivalent ischaemia, than a relative reduction in coronary blood flow during emotional stress, probably by coronary spasm, may be postulated as the most reasonable explanation for these observations.

Aged↗
PubMed1979

An exercise testing program for large populations.

A demonstration cardiovascular evaluation and exercise testing program was assessed for feasibility, cost, and accuracy. More than 1,800 people were examined in three years. The conditions of as many as 55 people per day were examined at a cost of $60 to $70 each. Abnormalities uncovered were similar to those observed in other studies. The program was considered successful in rendering services conveniently at low cost and with accuracy.

Adult↗
PubMed1978

Decreased VO2 consumption during exercise with elicitation of the relaxation response.

Oxygen consumption is usually considered to be predictable and unalterable at a fixed work intensity. The relaxation response is hypothesized to be an integrated hypothalamic response which results in generalized decreased sympathetic nervous system activity. One physiologic manifestation of the relaxation response is decreased oxygen consumption. The possibility that the elicitation of the relaxation response could decrease oxygen consumption at a fixed work intensity was investigated. Oxygen consumption was decreased 4 percent (p less than 0.05) in eight subjects working at a fixed intensity when the relaxation response was simultaneously elicited.

Female↗
PubMed1976

Morphological features of red blood cells in subjects with sickle cell trait: changes during exercise.

Occasional complications and even death in subjects with sickle cell trait have been attributed to severe physical exertion. However, the extent to which sickling actually occurs during exercise has not been reported. This study examined the red blood cell morphological features immediately following near maximal upright graded bicycle exercise in five asymptomatic black subjects with hemoglobin AS. Exercise produced minimal sickling in vivo, which was not proportional to the intensity of exercise. The amount of sickling in vivo was small in comparison to that observed in the presence of severe hypoxia in vitro, never exceeding 0.75%. in seven normal subjects with hemoglobin AA, exercise did not cause changes in red blood cell morphological features. We conclude that exercise may initiate sickling in subjects with sickle cell trait.

Adult↗
PubMed1976

The quiz electrocardiogram: a new diagnostic and research technique for evaluating the relation between emotional stress and ischemic heart disease.

To evaluate possible cardiovascular effects of emotional stress, a specially designed 12 minute tape-recorded stress quiz was administered to 43 subjects while blood pressure and the electrocardiogram were monitored. For the entire group, the heart rate and blood pressure rose from respective control levels of 76 beats/min and 136/87 mm Hg to a mean during the quiz of 87 beats/min and 158/94 mm Hg. This difference was highly significant. Of the 43 subjects, 33 were classified as executives and 10 as nonexecutives. There were three groups of executives: control and angina with and without a history of hypertension. Both groups of executives with angina responded with a significantly higher heart rate than that of the executive control group. Blood pressure response was significantly greater in executives with angina and hypertension than in the other groups. Heart rate and systolic blood pressure responses to the quiz were lower in nonexecutives with angina than in executives with angina. During the quiz, 10 of 14 executives with angina had S-T segment depression greater than 0.5 mm; of these, 7 evidenced greater than 1.0 mm depression, andin 3 of these the depression was greater than 1.5 mm and in 2 greater than or equal to 2.0 mm. None of the executive control subjects had S-T depression greater than 0.5 mm Among nonexecutives, 2 had S-T depression greater than 0.5 mm but none greater than 1.0 mm S-T depression. Seventeen of the patients also were given a bicycle exercise tolerance test. There was a significant correlation between S-T depression in response to exercise and to the quiz (r = 0.63; P less than 0.01). The quiz electrocardiogram is presented as a new research technique and diagnostic test for evaluating the relation of emotional stress to ischemic heart disease.

Adult↗
PubMed1975

Cardiovascular responsiveness to beta-adrenergic stimulation and blockade in chronic hypoxia.

Previous studies have shown that exposure to high altitude results in an initial increase in heart rate, followed by a return to sea-level values within several days; circulating catecholamines rise progressively during this time. Nine conscious dogs were studied in normoxia (N) and after 10 days' exposure to 445 torr (CH). The mean (plus or minus SE) hematocrit was higher in CH (50 plus or minus 2 vs. 42 plus or minus 1%) while Pa-o2 (53 plus or minus 1 vs. 97 plus or minus 2 torr) and PaCO2 (27 plus or minus 1 vs. 35 plus or minus 1 torr) were lower than in N. A 3.5-fold increase in plasma norepinephrine above the N value was found in CH. Arterial pH, heart rate (HR), and mean femoral arterial pressure (MAP) did not differ significantly in N and CH. Isoproterenol (ISO), 0.5 mug/kg iv, produced an average increase in HR of 92 plus or minus 9 beats/min in N, but only 66 plus or minus 8 beats/min in CH (P smaller than .02). Reduction in MAP after ISO were similar. Pretreatment with propranolol, 0.15 mg/kg iv, reduced HR equally in N and CH without affecting MAP, but diminished the HR response to ISO significantly more in CH than in N. The attenuated chronotropic response to beta-adrenoceptor stimulation following chronic hypobaric hypoxia suggests a relative cardiac refractoriness secondary to an increased level of sympathetic activity.

Adrenergic beta-Agonists↗
PubMed1975

Aldosterone dynamics during graded exercise at sea level and high altitude.

Hormonal responses to graded exercise of eight low altitude residents were examined at sea level (SL) and after 1 (acute) and 11 (chronic) days at 4,300 m (HA). Caloric, water, and electrolyte intakes were controlled, as were temperature and humidity. Blood was sampled at rest and during light and moderate upright bicycle exercise (20 min at 40% and 75% of maximal O2 uptake, respectively). Mean VO2 max at HA was 27% lower than at SL. Resting plasma levels of aldosterone (Aldo), renin, and angiotensin II (A II) were significantly lower (P smaller than 0.05) on day 1 at HA compared to SL, but returned to SL values by day 11. Plasma cortisol values at rest were similar at SL and HA and were not significantly altered by light or moderate exercise. Renin, A II, and Aldo rose progressively with increasing workload in each environment. With acute HA, renin and Aldo were lower than at either SL or chronic HA. The chronic HA levels tended to approximate SL findings, implying adaptation. The data suggest that aldosterone is predominantly under the control of the renin-angiotensin system during graded exercise at sea level and that the response of this system is altered on acute high-altitude exposure.

Acclimatization↗
PubMed1975

Effect of altitude relocations upon AaDo2 at rest and during exercise.

The supine pulmonary venous admixture (shunt) has been measured at Cerro de Pasco, 4,350 m altitude in eight subjects native to high altitude (HAN) under resting condition. Alveolar-arterial O2 tension difference (AaDO2) was also determined at rest and during exercise. The same subjects were studied again after 10 days' sojourn at sea level in Lima at 150 m altitude. They were compared with four subjects from sea level (SLN) who were studied first at Lima and after 2 and 10 days at Cerro de Pasco. At altitude, AaDO2 was smaller in HAN than SLN both at rest and during exercise. Shunt was the same in both groups. It is concluded that HAN show more even ventilation/perfusion relationship (VA/Q) at altitude, probably due to their high pulmonary artery pressure. On the contrary, SLN show less even VA/Q on altitude exposure, since their shunt decreased 37%. At sea level, HAN increased their AaDO2 due partially to an increase of 110% in their shunt, and in part due to less even VA/Q as shown by augmented VD/VT ratios. Each group tended to have a more effective gas exchange in its own environment.

Adult↗
PubMed1975

Changes in serum and sweat magnesium levels during work in the heat.

Serial changes in serum magnesium (Mg2+) were assessed in unacclimatized males during treadmill exercise in a hot (49 degrees/27 degrees C, dry/wet bulb) environment. Eight subjects walked at 5.6 km/h on a 0% grade, and at 90 min of exercise had a mean heart rate of increase of 70 plus or minus 5 (S.E.) beats/min, rise in rectal temperature of 2.1 degrees plus or minus 0.1 degrees C, and a weight loss of 2.07 plus or minus 0.10 kg. There was a significant (p less than 0.01) decrease in mean serum Mg2+ concentration (control: 1.87 plus or minus 0.06 mEq/I; 45 min: 1.81 plus or minus 0.07; 90 min: 1.72 plus or minus 0.08). The Mg2+ concentration in sweat samples collected over 90 min of work in the heat averaged 0.28 mEq/I (range 0.13 to 0.45). Thus, in normal man, exercise in an hot, dry environment resulted in a fall in serum magnesium which was not wholly explicable on the basis of sweat loss of this ion.

Adolescent↗
PubMed1975

Growth hormone and catecholamine response to exercise in relation to physical training.

Exercise of moderate intensity results in an increase in growth hormone concentrations. During prolonged moderate work, growth hormone levels fall toward resting values, but training causes these levels to be maintained. Circulating norepinephrine increases with work, and the increment is less following physical training. The adjustments to endurance training may be mediated through the sympathetic nervous system.

Catecholamines↗