Drugs online research references
Gerontology. 1988;34(1-2):88-94.
Hormonal supply during physical exercise in elderly patients with ischemic heart disease.
Korkushko OV, Frolkis MV, Yaroshenko YT.
Institute of Gerontology AMS USSR, Kiev.
30 males, suffering from ischemic heart disease (IHD), and stable exertional angina pectoris, whose age ranged from 60 to 74 years and also 15 apparently healthy volunteers of the same age participated in the study. The IHD patients' blood displayed increased basal levels of adrenocorticotropic hormone (ACTH), cortisol, and met-enkephalins. During graded physical exercise two types of hormonal system response were established: in the first group of patients the plasma ACTH and cortisol levels were seen to rise at maximal threshold load, while in the second group the content of the above hormones declined. The first group of patients showed a less economical hemodynamic response to standard loading in comparison to the second group. A relation was found between changes in hemodynamic system and function of pituitary-adrenal system in elderly IHD patients during physical exercise. Inadequate ACTH and cortisol increase in the course of effects of stress contributed to IHD aggravation in old age, along with reduced tolerance to physical exercise. beta-Adrenoblocker, propranolol, influenced both types of hormonal response, thereby diminishing their shifts in physical stress.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2838399&dopt=Abstract
J Interv Card Electrophysiol. 1999 Mar;3(1):15-8.
Nonpharmacologic validation of the intrinsic heart rate in cardiac transplant recipients.
Strobel JS, Epstein AE, Bourge RC, Kirklin JK, Kay GN.
Department of Medicine, University of Alabama at Birmingham 35294, USA.
BACKGROUND: The maximum sinus rate during exertion in humans is inversely related to age. However, the sinus rate at rest is quite variable. The intrinsic heart (IHR) following pharmacologic blockade of autonomic tone with propranolol and atropine has been proposed as a test of sinus node function and is related to age by the linear regression equation: IHR = 118.1 - (0.57 x age). Whether this relationship exists for transplanted hearts for which the donor sinus node is denervated has not been determined. METHODS: The relationship between the resting heart rate and the age of the donor heart was examined in 103 patients 1 year following orthotopic cardiac transplantation in the absence of rejection or intercurrent illness. Patients receiving beta-blockers, calcium blockers, antiarrhythmic drugs, digitalis, theophylline, or with biopsy evidence of rejection or abnormal coronary arteriograms were excluded from analysis. RESULTS: The recipient age, left ventricular ejection fraction, pulmonary capillary pressure, cardiac index, donor heart ischemic time and cardiopulmonary bypass time did not correlate with the rate of the resting donor sinus node. The resting heart rate was inversely related to age of the donor heart by the linear regression equation: HR = 112.0 - (046 x age). CONCLUSION: The resting rate of the denervated sinus node is related to donor age with a regression equation that is similar, though slightly slower, than that predicted after pharmacologic autonomic blockade.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10354971&dopt=Abstract
Biochem Pharmacol. 1984 Jun 15;33(12):1969-76.
Biochemical and physiological adaptation to chronic propranolol treatment in the rat.
Cramb G, Griffiths NM, Aiton JF, Simmons NL.
The biochemical and physiological aspects of isoprenaline sensitivity in normotensive rats were examined during and after abrupt withdrawal of chronic propranolol treatment. Serum propranolol concentrations in rats chronically treated for one month (0.125% propranolol in drinking water: 75-100 mg/kg/day) ranged from 7 to 23 ng/ml. At the height of the blockade, rats showed a decreased responsiveness in vivo to isoprenaline-induced increase in heart rate and fall in blood pressure; the ED50 values for isoprenaline being increased some 20- and 4-fold respectively. There was a 180% increase in beta-receptor number in sarcolemmal membranes isolated from ventricular muscle of these animals, together with increased basal (290%), fluoride- (100%), forskolin- (80%) and isoprenaline-stimulated (125%) adenylate cyclase activity. Twenty-four hours after propranolol withdrawal, serum propranolol concentrations were reduced by over 95%. At this time rats exhibited increased chronotropic and blood pressure responses to i.v. isoprenaline, indicated by the reduced ED50 values (2-fold and 12-fold respectively compared to controls). In addition, cardiac sarcolemmal beta-receptor number and adenylate cyclase activities were still significantly elevated above those of controls; 35% increase in beta-receptor number and increases of 96, 26, 13 and 37% in basal, fluoride-, forskolin- and isoprenaline-stimulated adenylate cyclase activities respectively. Forty-eight hours after drug withdrawal serum propranolol concentrations were only just detectable at 0.5 +/- 0.1 ng/ml. Although sarcolemmal beta-receptor numbers were still elevated (23%) isoprenaline-stimulated adenylate cyclase activity had returned to control values. However, both the fluoride- and forskolin-stimulated enzyme activities were decreased below control values by 12 and 23% respectively, suggestive of a reduction in the catalytic capacity of the adenylate cyclase complex. In parallel with the reduction in beta-receptor number and adenylate cyclase activity, the chronotropic response to i.v. isoprenaline had also returned to control values. In contrast, the blood pressure response to i.v. isoprenaline was still elevated in these animals indicated by the 5-fold reduction in the ED50 value compared with control animals.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6329227&dopt=Abstract
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