





Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
An experimental study investigating the effects of dopamine infusions on pulmonary and systemic vascular resistance, mean pulmonary and aortic pressures, stroke volume, and heart rate. The study found significant changes in mean pulmonary and aortic pressures, left atrial pressure, mean aortic flow, and stroke volume at various dopamine doses.
What you will learn
Typology: Exams
1 / 9
This page cannot be seen from the preview
Don't miss anything!
Br. J. Pharmac. (1969), 37, 618-626.
Cardiology Division, Stanford Uniiversity School of Medicine, Palo Alto, (^) California 94305
Mean aortic flow increased at all four doses, while (^) heart rate showed no change.
at infusions of 25 and (^30) jig/kg per min.
Dopamine (3,4 dihydroxyphenylethylamine) is a naturally occurring catecholamine and is the direct biochemical precursor to norepinephrine (^) (Blaschko, 1957). Investi- gators have recently described the cardiovascular response to this agent in animals and in man (^) (McDonald & Goldberg, 1963; Black & Rolett, 1966, 1968). Vasocon- striction has been (^) noted in the femoral vascular bed (McDonald & Goldiberg, 1963). At low doses, however, a slight but significant drop in systemic vascular (^) resistance has been reported without significant change in heart rate or arterial pressure
studies demonstrate direct cardiac stimulation through (^) a beta-adrenoceptor mechanism (Black & Rolett, 1966). Studies in (^) both dogs and man offer evidence that dopamine is a selective renal and mesenteric vasodilator (McNay, McDonald &
& (^) Zimmerman, 1963). These properties make dopamine an attractive agent for the
Dopamine on pulmonary circulation
treatment of patients with acute cardiovascular failure and shock. Two (^) reports
have been published. Although dopamine has been considered for clinical use in
systemic circulation.
Methods
opened in the mid-line and the animals (^) were prepared to record changes in the
jugular vein. Left atrial pressures were measured by a flange-tipped PE 260
with a purse-string suture. Central aortic pressure was monitored through a PE 260 fluid-filled catheter placed in the ascending aorta via the right femoral artery. The
heparinized (4 U.S.P. units/ml.) saline (^) drip. All pressures were measured with Statham P23Db pressure transducers. Mean (^) pressures were electrically determined by integration of the phasic pressure tracings.
flow (^) meter (Biotronex, Silver Spring, Md.) placed around the ascending aorta distal to the (^) coronary arteries. Each aortic flow probe was calibrated ,by comparison
Aortic flow was used as (^) cardiac output for all of these studies, and aortic flow was assumed to equal pulmonary (^) blood flow. (^) The electrocardiogram was followed by means of subcutaneous electrodes placed in the (^) appropriate extremity. All record- ings were made on a multi-channel Beckman Model R (^) direct-writing oscillograph. The animals were intubated with a cuffed endotracheal tube and ventilated with a (^) Harvard respirator. Arterial blood samples were analysed frequently utilizing a
before any intervention and before killing each (^) animal. In order to determine pulmonary and systemic responses to dopamine, the drug was infused (^) for 10 min periods at doses of 8, 15, 25 and 30 pLg/kg per min. These doses were (^) administered in randomized fashion from animal to animal, and all infusions were delivered with a variable-speed (^) Harvard apparatus infusion pump. After control measurements, each infusion was begun and data recorded (^) throughout the 10 min infusion period. Because the animals reached steady state within (^5) min,
between infusions for each animal (^) to return to control.
Left atrial pressure
Mean left atrial (^) pressure fell (^) slightly but (^) significantly in (^) response to (^) dopamine infused at 15 jig/kg per min and rose (^) significantly when infused at (^30) ,g/kg per
TABLE 1. Haemodynamic response to dopamine Dose: (^8) jiglkg per min
PA mean pressure mmHg LA mean pressure mmHg Ao mean pressure mmHg PVR (^) mmHg/l. per min SVR mmHgf1. per min Flow ./mmin SV ml./beat Heart rate
PA (^) mean pressure mmHg LA mean pressure mmHg Ao mean pressure mmHg PVR mmHg/l. per min SVR mmHg/l. per min Flow b.!min SV (^) m]./beat Heart rate
PA mean pressure mmHg LA mean pressure mmHg Ao mean pressure mmHg PVR mmHg/l. per min SVR mmHg/1. per min Flow (^) l,bmin SV ml./beat Heart rate
PA mean pressure mmHg LA mean pressure mmHg Ao (^) mean pressure mmHg PVR mmHg1l. per min SVR (^) mmHg!l. per min
SV (^) ml.bbeat Heart rate
Control 17-2± 1- 7-54± 109-6±7- 6-7±0- 70-7±6- 1-6±0- 9-3±1- 172-4±6- Dose: 17-64±0- 7-1 1 0 108-5±4- 6-5±0- 66-9±7- 1-8±0- 9.6±1^1 180.9±5- Dose: 17.3±0- 7-4±1- 105-4±5- 6-5±0- 70-0±8- 1.7+0. 9-5± 1- 174-3±7. Dose: 16-9±0- 8-2±0- 98-6±6- 5-8±0- 63-4±5- 1-6±0- 9-5±0- 165-8±9-
Absolute change Significance 0-740-4 NS -0-4±0-4 NS -5-5±3-1 NS -0-4±0-2 NS -9-1±3-1 <0- 0-23±0-07 < 0- 0-4±0-5 NS 13-8±7-2 NS
0-5±04 NS -1-0±0-3 <^ 0- 2-7±7-3 NS -0-3±0-3 NS -6-9±3-1 NS 0-28±0-07 < 0- 0-8±0-5 NS 12-8±6-0 NS (^25) ,gg'kg per min 2-6±1-0 <0- -0-0±0-7 NS 22-6±8-1 < 0- -0-5±0-3 (^) NS -3-3±10-0 NS 0-51±0-12 < 0- 2-4±0-7 <0- 9-5±8-9 NS (^30) jig/kg per min 3-1±0-7 <0- 1-8±0-8 <0- 47-0±9-8 < 0- -0-2±0-2 NS 27-3±11-2 <0- 0-23±0-10 < 0- 3-7±1-4 <0- -5-8±6-5 (^) NS
5-0±2-7 NS -3.4±6-6 NS 4-2±2-9 NS -5-6±3-0 NS -12-6±4-0 <^ 0- 15-8±6-1 < 0- 6-6±6-2 NS 9-2±5-6 NS
2-3±2-1 NS -14.714-2 < (^0 ) 3-1±6.7 NS 4-0±4-6 NS -12-0±4-8 < 0- 17.8±4-4 < 0- 11-2±6-1 NS 7-4±3-5 NS
14-3±5-1 < 0- 2-0±10-4 NS 21.8±8-3 <0- 9-4±5-0 NS 2-0±11-5 NS 36-7+11-7 (^) <0- 28-1±9-5 <0- 6-3±5-0 NS
17-8±3- 21-5±9- 48-7± 12- -4-5±4- 41-4±16- 12-0±5- 42-4±18- -2-9±3-
<0- NS <0- NS <0- <0- NS NS Responses to dopamine at 5 min for all infusions. PA mean, Mean pulmonary artery pressure: LA (^) mean, mean left atrial (^) pressure; Ao (^) mean, mean aortic pressure; PVR, pulmonary vascular (^) resistance; SVR, systemic vascular (^) resistance; AoF, mean aortic flow; SV, stroke volume; HR, heart rate.
621
D. C. Harrison (^) and others
Aortic pressure
Aortic pressure did not change significantly with infusion of the two low (^) doses;
kg per min (Fig. 2, Table 1). It was impossilble to separate the responses to 8 and 15 ,g/kg per min. Pressor responses induced by (^) the high doses (25 and (^30) jag/kg
Mean aortic flow
administered.
P<0-0I 60
50 -
40 -
..I 1-^ 0- , 30.
c^
° 20 c 660 X
10
-*
P<0.
NS
NS
I I I 8 15 25
30
FIG. 2. Mean (^) change (%A) and standard errors of the (^) change in aortic (^) pressure produced by various concentrations of (^) dopamine are shown. No (^) significant changes were noted at 8 and (^15) ,ug/kg per min, whereas (^) significant increases were noted at 25 and 30 (^) jg/kg per min dopamine infusion. The increase^ at^30 pg/kg per min was (^) significantly greater than that at 25 p,g/kg per min.
D. C. Harrison and others
Systemic vascular resistance
ever, the increase in resistance demonstrated at 30 (^) ,ug/kg per min was significantly
Stroke volume
stroke volume significantly; however,^ infusions^ at 25 and 30^ ,ug/kg^ per^ min pro- duced statistically^ significant^ increases (Table^ 1).^ The response at higher^ doses^ was significantly greater than the response at low doses (P<005), but again it was
(^25) Ag/kg per min from 30 (^) ,ug/kg per min.
Blood gases
Discussion
the dopamine doses administered. Only at the higher doses (25 and 30 (^) ,gg/kg per
Increase in aortic pressure in response to larger doses^ of^ dopamine-25 and^30 jig/kg per min^ (Table^1 and^ Fig.^ 2)-are^ in^ accord with^ findings^ of^ other^ investi-
(^30) pg/kg per min was noted. This decrease in heart rate^ at^ the^ highest administered dose was (^) probably due to the activation of baroreceptors and other pressor receptor mechanisms by the increase in^ peripheral pressure. The systemic vascular^ response to^ dopamine was^ dose-dependent; a^ slight^ but significant decrease in^ resistance^ occurred^ at^ the^ two^ low doses^ (8^ and 15^ jig/kg
of beta-adrenoceptor stimulation.
the large pressor response.
These studies were (^) supported in (^) part by N.I.H. Grants Nos. HE-09058, HE-5709 and HE-05866, and a grant from the American Heart Association, No. 67-708.