Search PubMed⌕ Search

Biomedical subjects

G A Ford

Publications and source records attributed to G A Ford.

At least 37 records · Page 2Linked to original sources
PubMed2000

CYP2D6 and CYP2C19 genotypes of patients with terodiline cardiotoxicity identified through the yellow card system.

AIMS: Terodiline has concentration dependent QT prolonging effects and thus the potential for cardiotoxicity. Pharmacogenetic variation in terodiline metabolism could be responsible for cardiotoxicity. We sought to determine whether CYP2D6 (debrisoquine hydroxylase) or CYP2C19 (S-mephenytoin hydroxylase) status is a risk factor for terodiline cardiotoxicity. METHODS: Using the UK Yellow Card scheme to identify patients, blood samples were obtained from eight patients who survived ventricular tachycardia or torsades de pointes suspected to be due to terodiline, for determination of CYP2D6 and CYP2C19 genotypes. Genotype prevalence was compared with that in published general population groups. RESULTS: One patient was a CYP2D6 poor metaboliser (CYP2D6*4 homozygous) and a second was heterozygous for CYP2D6*4, a slightly lower frequency for these genotypes compared with the general population (P = 0.31). In the case of CYP2C19, one patient was a poor metaboliser and four were heterozygous for the variant CYP2C19*2 allele, compared with general population frequencies of 2% and 23%, respectively (P = 0.035). CONCLUSIONS: These findings suggest that debrisoquine poor metaboliser status is not primarily responsible for terodiline cardiotoxicity. However, possession of the CYP2C19*2 allele appears to contribute to adverse cardiac reactions to terodiline. The present study demonstrates the feasibility of using spontaneous adverse drug reaction reporting schemes to determine the contribution of genotype for metabolizing enzymes to uncommon adverse drug reactions.

Aged↗
PubMed2000

Relationship of baroreflex sensitivity and blood pressure in an older population.

OBJECTIVES: Ageing and hypertension are associated with reduced baroreflex sensitivity (BRS) in young and middle-aged populations. The effects of blood pressure level on BRS in the older population are unclear. We examined the association between blood pressure and BRS in older persons with blood pressure below 180 mmHg. METHODS: BRS, high (alphaHF 0.15-0.4 Hz) and low (alphaLF 0.04-0.15 Hz) frequency alpha-index, was determined in 75 normotensive subjects (aged 75 +/- 4 years, 41% female, 131 +/- 10/74 +/- 7 mmHg) and 64 untreated hypertensive subjects (aged 76 +/- 5 years, 48% female, 165 +/- 7/ 88 +/- 7 mmHg) by spectral analysis of 20 min continuous blood pressure and heart rate recordings using finger plethysmography. Subjects were recruited from 10 general practices and were taking no cardiovascular medications. RESULTS: High but not low frequency alpha-index was significantly blunted in hypertensive subjects (alphaHF 5.1 +/- 3.1 versus 8.4 +/- 7.4 ms/mmHg, P< 0.001 and alphaLF 4.7 +/- 3.0 versus 5.8 +/- 3.9 ms/mmHg, P= 0.07). Multivariate analysis of the relationship between age and blood pressure demonstrated systolic and to a lesser extent diastolic blood pressure were significant predictors of variance in BRS for alphaHF [systolic blood pressure (SBP) P< 0.0001, diastolic blood pressure (DBP) P< 0.05, r2 = 0.1] and alphaLF (SBP P=0.01, DBP P<0.05, r2 = 0.04). Age was not a significant predictor for either measure, in the 20 year range studied. CONCLUSIONS: In an older population blood pressure is associated with reduced BRS, particularly for the high frequency component. Such a change may place older subjects with hypertension at increased risk of orthostatic hypotension, vasovagal syncope and sudden cardiac death.

Aged↗
PubMed2000

Cognitive performance in hypertensive and normotensive older subjects.

Longitudinal studies suggest that hypertension in midlife is associated with cognitive impairment in later life. Cross-sectional studies are difficult to interpret because blood pressure can change with onset of dementia and the inclusion of subjects on treatment and with hypertensive end-organ damage can make analysis difficult. We examined cognitive performance in hypertensive and normotensive subjects without dementia or stroke >/=70 years of age. Cognitive performance was determined with the use of a computerized assessment battery in 107 untreated hypertensives (55 women, age 76+/-4 years, blood pressure, 164+/-9/89+/-7; range, 138 to 179/68 to 99 mm Hg) and 116 normotensives (51 female, age 76+/-4 years, 131+/-10/74+/-7; 108 to 149/60 to 89 mm Hg). Older subjects with hypertension were significantly slower in all tests (reaction time, milliseconds; simple, 346+/-100 versus 318+/-56, P<0.05; memory scanning, 867+/-243 versus 789+/-159, P<0.01; immediate word recognition, 947+/-261 versus 886+/-192, P<0.05; and delayed word recognition, 937+/-230 versus 856+/-184, P<0.05; picture recognition, 952+/-184 versus 894+/-137, P<0.01; spatial memory, 1390+/-439 versus 1258+/-394, P<0.01; excepting choice reaction time, 510+/-75 versus 498+/-72, P=0.08). Accuracy was also impaired in tests of number vigilance, 99.2+/-2.5% versus 99.9+/-0.9, P<0.01; delayed word recognition, 83.5+/-16 versus 87.9+/-9.8, P<0.01; and spatial memory 64+/-32 versus 79+/-20, P<0.001. Hypertension in older subjects is associated with impaired cognition in a broad range of areas in the absence of clinically evident target organ damage.

Aged↗
PubMed2000

Effects of the menopause, gender, and estrogen replacement therapy on vascular nitric oxide activity.

Changes in vascular nitric oxide (NO) activity may contribute to cardiovascular risk. We determined the effect of the menopause, gender, and estrogen replacement therapy on arterial vascular NO activity. Vascular NO activity and sensitivity were determined in 15 healthy premenopausal women (mean age, 48 yr), 12 postmenopausal women (51 yr), and 14 men (51 yr). The effects of 14 days of estrogen replacement therapy (625 microg conjugated estrogens) were studied in 20 healthy postmenopausal women (60 yr). Forearm blood flow responses to brachial arterial infusions of L-NG-monomethyl-arginine (L-NMMA), norepinephrine, glyceryl trinitrate (GTN), and serotonin were determined using venous occlusion plethysmography. Constrictor responses to L-NMMA were reduced in postmenopausal women (82 +/- 14, summary response, mean +/- SEM) and men (89 + 6) compared to premenopausal women (118 + 10; P < 0.05). Constrictor responses to norepinephrine were increased in males (125 +/- 13) compared to premenopausal (81 +/- 8) and postmenopausal (88 +/- 16) women (P < 0.05). No differences were observed in GTN or serotonin responsiveness. Constrictor responses to L-NMMA increased after estrogen replacement (132 +/- 7 vs. 89 +/- 14; P < 0.05), with no change in norepinephrine, GTN, or serotonin responses. The menopause and male gender were associated with reduced arterial NO activity. Two weeks of estrogen replacement therapy restored vascular NO activity to premenopausal levels. Changes in vascular NO activity may contribute to changes in cardiovascular risk associated with male gender, postmenopausal status, and estrogen replacement therapy. Increased alpha-adrenoceptor responsiveness may contribute to increased cardiovascular risk in males.

Arteries↗
PubMed1999

Stimulated nitric oxide release and nitric oxide sensitivity in forearm arterial vasculature during normotensive and preeclamptic pregnancy.

OBJECTIVE: We sought to determine whether the enhanced forearm vascular activity of nitric oxide during pregnancy and preeclampsia is associated with altered smooth muscle sensitivity to nitric oxide or with stimulated nitric oxide release. STUDY DESIGN: Forearm blood flow responses to brachial artery infusion of glyceryl trinitrate (a nitric oxide donor), serotonin (an endothelium-dependent nitric oxide-mediated agonist), and ritodrine (a beta-adrenergic receptor agonist) were studied in 10 nonpregnant women, 12 pregnant women, and 7 women with preeclampsia by means of strain-gauge plethysmography. Responses to each drug (maximum dilator response and the sum of the percentage of dilator responses to each drug) were compared by analysis of variance. RESULTS: Compared with nonpregnant women, pregnant subjects showed reduced responses to serotonin (summary response, 117 +/- 19 vs 221 +/- 30; P <.05). Responses to serotonin were reduced in the group with preeclampsia compared with those in the nonpregnant group (summary response, 71 +/- 28; P <.05) but did not differ from the responses in pregnant women. There were no differences between responses to glyceryl trinitrate and responses to ritodrine in any of the groups. CONCLUSION: Vascular smooth muscle sensitivity to nitric oxide is not altered in normal pregnancy or preeclampsia, but dilator responses to serotonin appear blunted. Alterations in serotonin receptor coupling to nitric oxide synthase, or a limitation of availability of the substrate for nitric oxide synthase (L-arginine) during pregnancy, could account for the reduction in stimulated nitric oxide release.

Adolescent↗
PubMed1999

Contribution of nitric oxide to beta2-adrenoceptor mediated vasodilatation in human forearm arterial vasculature.

AIMS: beta2-adrenoceptor agonists are generally considered to produce endothelium independent vasodilatation through adenylate cyclase. We determined whether nitric oxide contributes to beta2-adrenoceptor vasodilatation in human arterial vasculature. METHODS: Forearm blood flow responses to brachial intra-arterial infusions of ritodrine (2.5-50 microg min(-1)), a selective beta2-adrenoceptor agonist, were determined in 24 healthy, normotensive subjects (mean age 22 years, 5F) on two occasions with initial and concomitant administration of L-NMMA (800 microg min(-1)), an NO synthase inhibitor, or noradrenaline (5-30 ng min(-1)), a control constrictor not affecting basal NO activity. Responses to the endothelium dependent vasodilator scrotonin (n = 6) and an endothelium independent vasodilator GTN (n = 9) were also determined. RESULTS: Maximal dilatation to ritodrine during L-NMMA infusion (310+/-32%; mean+/-s.e.mean) was reduced compared to that during noradrenaline infusion (417+/-41%, P<0.05), as were summary responses (1023+/-101 vs 1415+/-130; P<0.05). Responses to GTN were unaffected by L-NMMA compared to noradrenaline; max 177+/-26 vs 169+/-20%, 95% CI for difference -33,48; P=0.68; summary response 361+/-51 vs 396+/-37, 95% CI -142,71; P=0.46. Dilator responses to serotonin were reduced by L-NMMA; max 64+/-20 vs 163+/-26%, P<0.01; summary response 129+/-36 vs 293+/-60; P<0.05) and to a greater extent than ritodrine (58+/-7 vs 25+/-14%, P<0.05). CONCLUSIONS: beta2-adrenoceptor mediated vasodilatation in the human forearm has an NO mediated component. The underlying mechanism for this effect is unclear, but flow mediated vasodilatation is unlikely to be responsible.

Adolescent↗
PubMed1999

Effect of age on plasma membrane asymmetry and membrane fluidity in human leukocytes and platelets.

BACKGROUND: We determined whether ageing changes in plasma membrane phospholipid asymmetry were related to changes in membrane physical characteristics. METHODS: Plasma membrane asymmetry was determined in polymorphonuclear leukocytes (PMN), lymphocytes, and platelets from 45 healthy young (mean 29 years, 26 male) and 28 healthy elderly (mean 70 years, 15 male) subjects by flow cytometric measurement of annexin V binding to cell surface phosphatidylserine. Membrane fluidity in lymphocytes and platelets from young and elderly subjects was determined by fluorescence polarization of 1,6-diphenyl- 1,3,5-hexatriene (DPH) and (4-trimethylammonium)-DPH (TMA). RESULTS: In elderly subjects, a higher proportion of lymphocytes had specific annexin V binding to phosphatidylserine (PS) than in young subjects (young: median percentage of cells with specific annexin V binding to PS 5.3 [second to fourth quintiles range 3.8-8.7]; elderly: 8.5 [5.2-17.2]; p = .028). No ageing change in annexin V binding to PMN was observed (young: 35.0% [21.8-53.5]; elderly: 39.6% [27.4-69.8]; p = .42). Platelets had no specific annexin V binding (young: median molecules of annexin V specific binding 3.8 [0.4-11.3]; elderly: -1.4 [-4.8-1.7]; p = .23). Superficial membrane fluidity was increased in lymphocytes (TMA anisotropy, young: 0.271 [0.259-0.289]; elderly: 0.262 [0.242-0.279];p = .004), but not in platelets (young: 0.273 [0.259-0.293]; elderly: 0.269 [0.248-0.284]; p = .12). Lymphocyte annexin V binding correlated with TMA (r = -.65, p = .022), but not DPH anisotropy (r = -.39, p = .18). CONCLUSIONS: Plasma membrane asymmetry is decreased with age in human lymphocytes, but not in human PMN or platelets. The increased proportion of lymphocytes with loss of plasma membrane asymmetry corresponds to the ageing changes in superficial membrane fluidity observed in lymphocytes. Such alterations in lymphocyte plasma membrane structure with age could account for changes in membrane-bound receptor function described with ageing, and may contribute to alterations in immune responsiveness and vascular thrombosis seen in older humans.

Adult↗
PubMed1999

Nitric oxide activity in the peripheral vasculature during normotensive and preeclamptic pregnancy.

We investigated the role of nitric oxide (NO) in the vascular resistance changes of normotensive and preeclamptic pregnancy. Forearm blood flow (FBF) responses to brachial artery infusion of N(G)-monomethyl-L-arginine (L-NMMA), an NO synthase inhibitor, and angiotensin II (ANG II), an NO-independent vasoconstrictor, were determined by plethysmography in 20 nonpregnant women, 20 normotensive primigravidae, and 15 primigravidae with untreated preeclampsia. In pregnant subjects, FBF was reduced to nonpregnancy levels by infusion of norepinephrine (NE), which was then coinfused with ANG II (2, 4, and 8 ng/min) and L-NMMA (200, 400, and 800 microgram/min) each for 5 min. In separate studies, responses to NE (20, 50, and 100 ng/min) were determined in 8 nonpregnant women, with FBF elevated to pregnancy levels by concomitant infusion of glyceryl trinitrate, and 10 pregnant women. Vasoconstrictor responses to L-NMMA were increased in pregnant compared with nonpregnant subjects [mean +/- SE summary measure (in arbitrary units): 60 +/- 7 vs. 89 +/- 8, respectively; P < 0.01], whereas responses to ANG II were blunted (125 +/- 11 vs. 79 +/- 7, respectively; P < 0.001). Compared with normotensive pregnant subjects, preeclamptic subjects had an enhanced response to ANG II (79 +/- 7 vs. 103 +/- 8, respectively; P < 0.05) but no difference in response to L-NMMA (89 +/- 8 vs. 73 +/- 10, respectively; P = 0.30). Responses to NE were similar in pregnant and nonpregnant subjects (110 +/- 20 vs. 95 +/- 33, respectively; P = 0.66). During the third trimester of pregnancy, forearm constrictor responses to L-NMMA are increased. The responses to NE are unchanged, whereas responses to ANG II are blunted. Increased NO activity contributes to the fall in peripheral resistance. In preeclampsia, forearm constrictor responses to ANG II but not L-NMMA are increased compared with those in normal pregnancy. Changes in vascular NO activity are unlikely to account for the increased vascular tone in this condition.

Adult↗
PubMed1999

Effect of aging on CD11b and CD69 surface expression by vesicular insertion in human polymorphonuclear leucocytes.

The exocytosis of intracellular vesicles is an important function of the plasma membrane, which is responsible for hormone secretion, cell surface expression of antigens, ion transporters and receptors, and intracellular and intercellular signalling. Human aging is associated with many physiological and cellular changes, many of which are due to alterations in plasma membrane functioning. Alterations in vesicle externalization with age could account for many of these changes. We investigated whether alterations in vesicle exocytosis occur with increasing age by flow-cytometric determination of CD11b and CD69 expression on the surface of human polymorphonuclear leucocytes (PMN) stimulated with phorbol myristate acetate (PMA), a tumour promoter which binds to and activates protein kinase C (PKC) directly, or with formyl-Met-Leu-Phe (fMLP), which activates PKC indirectly via interactions with a cell surface receptor and G-protein, and subsequent inositol phosphate hydrolysis. Following stimulation with PMA, a decrease in the proportion of PMN expressing CD69 at high levels was observed in elderly compared with young subjects (young, 55.3%; elderly, 43.9%; P=0.01). No aging-related differences in the proportion of PMN expressing CD11b (young, 73.7%; elderly, 68.4%; P=0.15), or in the number of molecules of CD69 or CD11b expressed per cell, were observed. Stimulation with fMLP or low PMA concentrations resulted in full CD11b expression but minimal CD69 expression in both young and elderly subjects. Cells which expressed CD69 had no CD11b expression, while those cells expressing CD11b had minimal CD69 expression. Thus the PMA-induced expression of CD11b and CD69 in human PMN represents two separate processes, only one of which is affected in aging. CD11b expression appears to require a lesser degree of PKC stimulation compared with that required for CD69 expression. The age-associated reduction in PMA-stimulated CD69 expression may occur either at or distal to PKC activation. Such a decrease may contribute to the age-associated impairments in PMN function that contribute, in turn, to immunosenescence.

Adult↗
PubMed1999

Are postal questionnaire surveys of reported activity valid? An exploration using general practitioner management of hypertension in older people.

BACKGROUND: Postal questionnaire surveys are commonly used in general practice and often ask about self-reported activity. The validity of this approach is unknown. AIM: To explore the criterion validity of questions asking about self-reported activity in a self-completion questionnaire. METHOD: A comparison was made between (a) the self-reported actions of all general practitioner (GP) principals in 51 general practices randomly selected within the nine family health services authorities of the former northern regional health authority, and (b) the contents of the medical records (case notes and computerized records) of patients classified as hypertensive from a 1 in 7 random sample of all patients registered in these practices and aged between 65 and 80. Data were gathered from the GPs by self-completion postal questionnaires. Six comparisons were made for two groups of items: first, target and achieved blood pressure; secondly, patient's weight, smoking status, alcohol consumption, exercise and salt intake. The frequency with which the data items were recorded in patient records was compared with the GPs' self-reported frequency of performing the actions. RESULTS: No relationship was found between achieved blood pressure and stated target levels. For each of the other actions, more than half of the responders reported that they usually or always performed the activity. For four of these (smoking, weight, alcohol and exercise), a significant association was noted, but the size of this varied considerably. CONCLUSIONS: There is a variable relationship between what responders report that they do in self-completion questionnaires, and what they actually do as judged by the contents of their patients' medical records. In the absence of prior, knowledge of the validity of questions on reported activity, or of concurrent attempts to establish their validity, the questions should not be asked.

Aged↗
PubMed1997

Mitochondrial function in muscle from elderly athletes.

The extent to which mitochondria are involved in the aging process is controversial; much of the reported decline in mitochondrial oxidations in human skeletal muscle may be due to disease and inactivity rather than age. To study true aging, mitochondrial respiratory chain function was studied in 9 young and 12 elderly athletes. No significant deterioration with age was observed. If mitochondria are involved in aging, it must be through a more subtle mechanism than a global decline in respiratory chain activity.

Adult↗
PubMed1997

Defining hypertension in older people from primary care case notes review.

A method of defining blood pressure (BP) status from a review of primary care patient records was developed and then validated using the case notes of a general practitioner with an interest in hypertension. Data were drawn from the records of the previous 6 years of all 65 to 80-year-old patients in the practice (n = 263). Patients were then categorised as hypertensive, normotensive or 'undetermined' by using a flowchart based on the mean of the three most recent BP measurements, antihypertensive medication and comorbidities of ischaemic heart disease, myocardial infarction, angina, oedema or cardiac failure. Mean systolic BP of > or = 160 mm Hg and/or diastolic BP of > or = 90 mm Hg were used as a threshold definition of hypertension and of BP control. Disagreement between general practitioner and the notes based definition occurred in 11% of patients (5% hypertensive, 6% normotensive). Reasons for disagreement were: controlled hypertensives with comorbidities such as angina or heart failure (4%), isolated elevated readings (3%), use of antihypertensive medication for separate indications (2%), other reasons (2%). The resulting sensitivity and specificity was 86% and 88% respectively. Including the recording of a diagnosis of hypertension in the definition increased the sensitivity to 98% with specificity unchanged at 88%. Actual sensitivity of the instrument when used in other practices is likely to lie between 88% and 98% depending on the quality of the doctor's recording of the diagnosis of hypertension. These findings suggest that data from primary care case notes can provide a ready and valid means of defining cases of hypertension for studying the management of hypertension in primary care and for research purposes.

Aged↗
PubMed1997

Doctors' attitudes towards the detection and treatment of hypertension in older people.

Within the former northern region a questionnaire was sent to a one in two random sample of general practitioners and to consultant physicians involved in the treatment of older hypertensive patients, to determine current attitudes of doctors to the management of hypertension in older people. A total of 407 general practitioners and 125 consultant physicians (including 38 consultant geriatricians) completed the questionnaire; response rates of 58% and 73% respectively. The median (range) threshold level for intervention of an otherwise well 75-year-old patient was 180 (140-240)/100 (90-120) mm Hg for general practitioners as against current recommendations of > or = 160/90 mm Hg. Geriatricians adopted significantly lower thresholds than both general practitioners and other specialists. Target blood pressure (BP) and drug therapy were in line with British Hypertension Society recommendations. The majority of general practitioners stated that they would initiate treatment for hypertension later, be less aggressive in their treatment and accept higher levels of BP than with younger patients. Approximately half perceived compliance and lifestyle changes as problematic in older people, while approximately a third were concerned about the problems created by drug treatment and uncertainty about the practicality of treating all older hypertensive patients. A quarter expressed reluctance to initiate hypertensive treatment because of side effects and to treat isolated systolic hypertension. These stated attitudes amongst general practitioners may explain the continuing conservatism in the management of hypertension. This study found considerable variation in diagnostic threshold between doctors, which suggests that current management of hypertension in older people is likely to vary significantly.

Aged↗
PubMed1997

A pharmacokinetic and pharmacodynamic interaction study between nebivolol and the H2-receptor antagonists cimetidine and ranitidine.

AIMS: The study was designed to investigate the effects of the H2-receptor antagonists, cimetidine and ranitidine on the pharmacokinetics and pharmacodynamics of nebivolol in healthy volunteers. METHODS: Twelve healthy volunteers took part in a randomized placebo-controlled cross-over study. Each subject received on three separate occasions placebo, cimetidine (400 mg twice daily) or ranitidine (150 mg twice daily) for 24 h before and 48 h after a single oral dose of nebivolol (5 mg). Nebivolol and its individual (+) and (-) enantiomers were determined tby h.p.l.c. RESULTS: Ranitidine had no significant effect on nebivolol pharmacokinetics. Cimetidine, however, resulted in a 21-23% increase in Cmax of unchanged nebivolol and of each enantiomer plus its hydroxylated metabolites. Cimetidine significantly (p < 0.05) increased the AUC [mean +/- s.d. (95% C.I. of differences in mean)] for unchanged (+/-)-nebivolol [7.76 +/- 3.07 ng ml-1 h with placebo; 11.50 +/- 5.40 (1.75, 8.76) ng ml-1 h with cimetidine], (+)-nebivolol plus its hydroxylated metabolites [73.0 +/- 18.0 ng ml-1 h with placebo; 91.5 +/- 25.7 (1.0, 23.1) ng ml-1 h with cimetidine] and (-)-nebivolol plus its hydroxylated metabolites [101 +/- 32 ng ml-1 h with placebo; 123 +/- 38 (3.3, 27.0) ng ml-1 h with cimetidine]. Statistical analysis of the resting blood pressure and heart rate and exercise data did not suggest any consistent effects of ranitidine or cimetidine upon the pharmacodynamic effects of nebivolol. CONCLUSIONS: There was no interaction between ranitidine and nebivolol. Although cimetidine inhibited nebivolol metabolism, it did not have a significant influence on the pharmacodynamics of the drug.

Adult↗
PubMed1997

Effects of aerobic exercise training and yoga on the baroreflex in healthy elderly persons.

It is unclear whether the age-associated reduction in baroreflex sensitivity is modifiable by exercise training. The effects of aerobic exercise training and yoga, a non-aerobic control intervention, on the baroreflex of elderly persons was determined. Baroreflex sensitivity was quantified by the alpha-index, at high frequency (HF; 0.15-0.35 Hz, reflecting parasympathetic activity) and mid-frequency (MF; 0.05-0.15 Hz, reflecting sympathetic activity as well), derived from spectral and cross-spectral analysis of spontaneous fluctuations in heart rate and blood pressure. Twenty-six (10 women) sedentary, healthy, normotensive elderly (mean 68 years, range 62-81 years) subjects were studied. Fourteen (4 women) of the sedentary elderly subjects completed 6 weeks of aerobic training, while the other 12 (6 women) subjects completed 6 weeks of yoga. Heart rate decreased following yoga (69 +/- 8 vs. 61 +/- 7 min-1, P < 0.05) but not aerobic training (66 +/- 8 vs. 63 +/- 9 min-1, P = 0.29). VO2 max increased by 11% following yoga (P < 0.01) and by 24% following aerobic training (P < 0.01). No significant change in alpha MF (6.5 +/- 3.5 vs. 6.2 +/- 3.0 ms mmHg-1, P = 0.69) or alpha HF (8.5 +/- 4.7 vs. 8.9 +/- 3.5 ms mmHg-1, P = 0.65) occurred after aerobic training. Following yoga, alpha HF (8.0 +/- 3.6 vs. 11.5 +/- 5.2 ms mmHg-1, P < 0.01) but not alpha MF (6.5 +/- 3.0 vs. 7.6 +/- 2.8 ms mmHg-1, P = 0.29) increased. Short-duration aerobic training does not modify the alpha-index at alpha MF or alpha HF in healthy normotensive elderly subjects. alpha HF but not alpha MF increased following yoga, suggesting that these parameters are measuring distinct aspects of the baroreflex that are separately modifiable.

Aged↗
PubMed1997

Baroreflex function in sedentary and endurance-trained elderly people.

OBJECTIVE: to determine the differences associated with age and endurance exercise training on the baroreflex function of healthy subjects. DESIGN: cross-sectional study. SETTING: university research department. PARTICIPANTS: 26 (10 female) sedentary, healthy, normotensive elderly subjects (mean age 67 years, range 62-81), eight (two female) elderly endurance-trained athletes (66 years, 62-69) and eight (two female) young (30 years, 25-34) subjects. MEASUREMENTS: baroreflex sensitivity was quantified by the alpha-index, at high frequency (HF, 0.15-0.35 Hz) and mid frequency (MF, 0.05-0.15 Hz), derived from spectral and cross-spectral analysis of spontaneous fluctuations in heart rate and blood pressure. RESULTS: resting heart rate was significantly lower in endurance-trained athletes than sedentary elderly people (58 +/- 12 versus 68 +/- 11 min(-1), P < 0.05) but not different to that in healthy young subjects (63 +/- 9 min[-1]). alpha(HF) in sedentary elderly subjects (8.1 +/- 4.2 ms.mm Hg[-1]) was lower than both endurance-trained elderly athletes (14.8 +/- 4.8 ms.mm Hg(-1), P < 0.05) and healthy young subjects (28.3 +/- 21.8 ms.mm Hg(-1), P < 0.05) and was not significantly different between endurance-trained elderly athletes and healthy young subjects (P = 0.10). alpha(MF) in healthy young subjects (15.4 +/- 8.8 ms.mm Hg[-1]) was greater than in sedentary elderly subjects (6.5 +/- 3.2 ms.mm Hg(-1), P < 0.01) and endurance-trained elderly athletes (6.9 +/- 2.0 ms.mmHg(-1), P < 0.01), while there was no significant difference between the two elderly groups (P = 0.66). CONCLUSIONS: both components of the baroreflex measured by the alpha-index show a decrease with age. Elderly endurance-trained athletes have less reduction in the high, but not mid, frequency component of the alpha-index compared with sedentary elderly subjects. Some of the age-related changes in baroreflex sensitivity may be related to physical fitness and activity levels.

Adult↗