title: Acute changes in forearm venous volume and tone using radionuclide plethysmography.
abstract: In this investigation blood pool scintigraphy was validated as a method to study acute changes in human forearm veins. Changes in regional forearm vascular volume (capacity) and the occluding pressure-volume (P-V) relationship induced by sublingual nifedipine (NIF) and nitroglycerin (GTN) were recorded in 16 patients with simultaneous data collection by the radionuclide and the mercury-in-rubber strain-gauge techniques. The standard error of estimate (Syx) between successive control measurements using the radionuclide method was 3.1% compared with 3.2% for the strain-gauge method. The venous P-V curves were highly reproducible using both techniques. Strain gauge and radionuclide measurements of acute changes in forearm venous volume correlated well (r = 0.86; Syx = 7%, n = 156). After 20 mg of NIF or 0.6 mg of GTN, mean heart rate increased from 71 +/- 10 to 77 +/- 9 and from 68 +/- 10 to 75 +/- 11 beats/min, respectively, and group systolic blood pressure decreased from 128 +/- 22 to 120 +/- 19 and from 136 +/- 18 to 126 +/- 23 mmHg, respectively (P less than 0.05). At venous occluding pressures of 0 and 30 mmHg, the forearm vascular volume did not change after NIF (2 +/- 4 and -1 +/- 4%; P greater than 0.05), whereas it increased after GTN (8 +/- 5 and 12 +/- 7%; P less than 0.001). The forearm venous P-V relationship did not change after NIF, whereas a significant rightward shift (venodilation, with an increase in unstressed volume) occurred after GTN.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, University of Calgary, Alberta, Canada.
authors.forename: D E
authors.initials: DE
authors.lastname: Manyari
authors.forename: T J
authors.initials: TJ
authors.lastname: Malkinson
authors.forename: V
authors.initials: V
authors.lastname: Robinson
authors.forename: E R
authors.initials: ER
authors.lastname: Smith
authors.forename: K E
authors.initials: KE
authors.lastname: Cooper
mesh_terms: D005542:Forearm / Q000098:blood supply*; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000502:physiology / Q000503:physiopathology; D010991:Plethysmography / Q000379:methods; D013667:Technetium; D014680:Veins / Q000502:physiology* / Q000503:physiopathology
chemical_list: D013667:Technetium