Biomedical subjects

R C Allison

Publications and source records attributed to R C Allison.

28 records · Page 2Linked to original sources

PubMed1984

Effects of histamine, serotonin, and norepinephrine on circulation of dog lungs.

The action of histamine (H), serotonin (5-HT), and norepinephrine (NE) on the lung vasculature was evaluated in isolated blood-perfused dog lung lobes using isogravimetric techniques. Pre- and postcapillary resistances, isogravimetric capillary pressure (Pc,i), capillary filtration pressure (Pc,f), capillary filtration coefficient (Kf,c), and vascular pressure-volume relationships were measured. For constant-flow conditions, all drugs induced marked increases in both pre- and postcapillary resistances and increased Pc,f. The rise in Pc,f was most pronounced for H and least marked for NE and 5-HT. For constant-pressure perfusion, Pc,f increased slightly for H but not for NE and 5-HT, while total vascular resistance increased 4-5 times for all drugs. Vascular distensibility and volumes decreased markedly for NE and 5-HT but only slightly for H. None of the drugs appeared to alter capillary permeability because Kf,c and Pc,i measured during the infusions were not different from control.

Animals↗

PubMed1983

Effect of air embolism on the measurement of extravascular lung thermal volume.

To determine the accuracy of thermal-dye indicator-dilution measurements of lung water during perfusion abnormalities, we embolized air into the lungs of 10 dogs anesthetized with pentobarbital and mechanically ventilated. A control period was followed by a period of air injection (10 ml) and subsequent air infusion (E1), a second period of air injection and infusion (E2), and a recovery period. Thermal and dye-dilution curves were obtained during each period, and cardiac output (CO), total thermal volume, intravascular volume, and extravascular thermal volume (ETV) were calculated. Pulmonary arterial pressure (Ppa) increased from 16 +/- 2 cmH2O during control to 29 +/- 3 cmH2O during E1 and to 40 +/- 3 cmH2O during E2 and decreased to 21 +/- 2 cmH2O during recovery. CO did not change, and pulmonary vascular resistance changed in a pattern similar to Ppa. ETV fell from 113 +/- 8 ml during control to 59 +/- 11 ml during E1 and to 29 +/- 9 ml during E2 and rose to 136 +/- 23 ml during recovery. There was no increase in extravascular lung water or mass determined gravimetrically at the end of the experiments. We conclude that the thermal-dye technique will underestimate lung water in nonedematous lungs if emboli prevent complete diffusion of the thermal indicator.

Animals↗

PubMed1981

Role of platelet serotonin in the canine pulmonary response to endotoxin.

There is evidence suggesting a role for platelet serotonin (5-HT) in the immediate pulmonary response to endotoxin in the dog (J. Appl. Physiol. 23: 47, 1967). To further define this role, autologous canine platelets were labeled with 5-[14C]HT in vitro and then reinfused. Subsequently Escherichia coli endotoxin (0.55:B-5, Difco), 2.5 mg/kg, was injected. Within 5 min dynamic compliance (CL) fell by more than 50%, and nonelastic resistance (RL) increased by more than 200%. Despite a 95% decrease in platelet count, less than 10% of the platelet 5-HT was released as determined by changes in the radioactivity of platelet-poor plasma (PPP) prepared from both aortic and pulmonary artery blood. As a positive control, injected of bovine collagen produced a similar decrease in platelet count that was associated with a significant increase in the radioactivity of aortic and pulmonary artery PPP. FInally, rapid injection of a dose of 5-HT equivalent to 25% of the 5-HT in circulating platelets did not cause a change in CL or RL equivalent to that produced by endotoxin. From these data we conclude that endotoxin injection does not cause immediate massive platelet activation and that platelet 5-HT does not play a major role in the immediate pulmonary response to endotoxin.

Animals↗

PubMed1981

Effect of methysergide on the acute lung mechanics response to endotoxin.

The effect of the serotonin antagonist methysergide on the acute lung mechanics response to endotoxin in anesthetized, paralyzed, mechanically ventilated dogs was investigated. In five dogs given 0.25 mg/kg Escherichia coli endotoxin only, the pulmonary nonelastic resistance (RL) increased to 238% of control and dynamic compliance (CL) decreased to 50% of control. In a second group of five dogs, methysergide (0.25 mg/kg) was shown to markedly attenuate the lung mechanics response to serotonin (0.04 mg/kg), which alone had produced changes in lung mechanics greater than endotoxin. In these same dogs endotoxin administered after injection of methysergide produced an increase in RL to 377% and a decrease in CL to 33% of control. In a third group of five dogs whose lung mechanics response to serotonin was also greater than to endotoxin alone, endotoxin administered after injection of saline produced an increase in RL to 168% and a decrease in CL to 58% of control. Since the response to endotoxin after injection of methysergide exceeded the response after saline, we conclude that serotonin is not a mediator of the acute lung mechanics response to endotoxin.

Animals↗

PubMed1981

Edema affects intra-alveolar fluid pressures and interdependence in dog lungs.

The pressures in occluded, fluid-filled segments of lung were measured in closed-chest supine dogs ventilated with positive pressure at a constant tidal volume. Segment fluid pressures decreased in response to lung inflation and were used with esophageal and airway pressures to calculate an index of bronchiolar-parenchymal interdependence. Animals were subjected to three sequential 5% body wt infusions of Tyrode's solution followed by a 20- to 30 min-recovery period after each infusion. The interdependence index decreased significantly following each infusion, with infusions as small as 1% body wt producing a detectable decrease. The mean pressures in the Tyrode's solution-filled segments generally increased in response to the infusions, but the time course of the response was variable. The base-line pressure in Tyrode's solution-filled segments was -4.8 +/- 2.4 cmH2O. This increased to -1.1 +/- 2.7 cmH2O after a total of 15% body wt had been infused. At the same time, extravascular lung water increased by approximately 17%. Thus negative collapse pressures in the occluded segments were opposed by mechanical stresses transmitted through alveolar wall attachments. This counterbalancing stress was consistently reduced by both increased tissue hydration and increased pulmonary vascular pressure.

Animals↗

PubMed1975

Immunological status as a criterion for operability of genitourinary cancers.

Delayed hypersensitivity reaction of 116 consecutive cases of urologic cancers were studied by skin tests. Ninety-one percent of those who were operable or free of diseases at least six months had positive skin reaction. All patients with inoperable or recurrent bladder, kidney, or testis tumor had negative skin reaction. All patients with operable prostatic cancer and 52% of those with inoperable prostatic cancer had positive skin reaction. Skin testing could provide useful data regarding the extent of tumor and operability. It is proposed that skin testing be included in routine preoperative evaluation of urologic cancers.

Adolescent↗

PubMed1974