Biomedical subjects

W F Hofman

Publications and source records attributed to W F Hofman.

41 records · Page 3Linked to original sources

PubMed1977

Effects of electroanesthesia and a phenothiazine tranquilizer on thermoregulation in the sheep.

The effects of giving propiopromazine alone and of electroanesthesia-propiopromazine treatment on thermoregulation (body temperature regulation) were studied in 3 sheep at ambient temperatures of 5, 25, and 35 C. Measures of thermoregulation during a 120-minute treatment and 120-treatment recovery period included rectal temperature, respiratory frequency, respiratory evaporative heat loss, metabolic heat production, multiple skin temperatures, and shivering. During cold exposure (5 C), both the propiopromazine administration and the electroanesthesia-propiopromazine treatment resulted in hypothermia which was attributed to increased peripheral and respiratory heat losses, a transient inhibition of shivering thermogenesis, and a reduction in metabolic heat production. At 35 C ambient temperature, both resulted in hyperthermia caused principally by a reduction in respiratory evaporative heat loss. The effects of electroanesthesia-propiopromazine treatment on thermoregulation appeared to be additive at both the cold (5 C) and the hot (35 C) environments, in that simultaneous administration resulted in a more profound thermoregulatory impairment. Nevertheless, shifts in body temperature during electroanesthesia are partly attributable to phenothiazine premedication.

Animals↗

PubMed1977

Cardiorespiratory and behavioral reactions to the lidocaine-induced convulsions in the dog.

Central nervous system (CNS) reactions to intermittently infused lidocaine HCl (i.v.) were evaluated from cardiorespiratory and behavioral responses in 33 mongrel dogs. Threshold convulsive doses were established for each of three distinct and predictable seizure patterns. The first seizure activity observed was tonic extension (TE) which occurred at an infused lidocaine dose of 12.2+/-0.6 mg/kg followed by running activity after 22.7+/-0.9 mg/kg lidocaine was given. The threshold for intermittent tonic-clonic seizures (ICS) occurred at an infused lidocaine dose of 33.3+/-1.5 mg/kg. Mean blood pressure and pulse pressure increased at the onset of TE and ICS, with a decline in arterial pH and PCO2 during the ICS. No relationship was found between the animals' acid-base status and the ICS threshold. Toxicity to lidocaine in the dog is expressed by distinct behavioral responses suggesting lidocaine may affect various parts of the CNS. The mongrel dog appears to be a satisfactory and simple model system to evaluate lidocaine toxicity from behavioral and cardiorespiratory responses.

Animals↗

PubMed1976

Myocardial function during hypoxia in the presence of different buffers.

Electrically driven rabbit left atria were exposed to 20 min periods of either hypoxia or anoxia in the presence of a bicarbonate-phosphate buffer, a Tris buffer [tris (hydroxymethyl) aminomethane hydrochloride] or combination of both. The bicarbonate-phosphate buffer system was shown to be important for tissue survival during hypoxia or anoxia whereas recovery was diminished in the presence of Tris only. Stimulus threshold and arrhythmias were shown to increase for atria in Tris. Oxygen consumption determinations on both spontaneously beating right atria and quiescent left atria showed no difference between pre- and post-hypoxia or between different buffers. Tris was shown to elicit a positive inotropic effect without an increase in O2 consumption.

Animals↗

PubMedDate not supplied

Methylene blue restores vasodilation to bradykinin after inhibition of nitric oxide production in the isolated dog lung.

Methylene blue (MB) is a widely used putative inhibitor of nitric oxide (NO)-dependent responses, particularly in cell culture and vascular ring studies. MB is postulated to diminish vasodilation to NO either by preventing activation of guanylate cyclase by NO or by oxidizing NO formed by NO synthase. In the present study we examined whether MB inhibited vasodilation to bradykinin (BK) in the cyclooxygenase-inhibited, isolated canine lung lobe perfused with blood at constant flow. One group of lobes (n = 5) was challenged with BK at baseline vascular tone, after tone was doubled by infusion of serotonin (5-HT), and again after MB treatment. Bradykinin challenge failed to evoke a depressor response at baseline vascular tone but induced marked vasodilation after vascular tone was increased by 5-HT. Subsequent treatment with MB, however, failed to significantly diminish vasodilation to BK (p > 0.05). A second group of lobes (n = 4) was challenged with BK after cyclooxygenase inhibition and the doubling of vascular tone with serotonin infusion. The dose-dependent vasodilation to BK was diminished (p < 0.01) after treatment with 1.8 mM N omega-nitro-L-arginine (L-NA), a potent inhibitor of nitric oxide synthase. However, subsequent treatment with MB restored the vasodilator response to bradykinin to pre-L-NA values (p < 0.01). While our results suggest that vasodilation to bradykinin is mediated in part by NO formation, MB treatment does not appear to alter BK-induced vasodilation, and even enhanced vasodilation to bradykinin after L-NA. MB appears to have some nonspecific effects on vascular tone and reactivity that are unrelated to NO formation.

Animals↗

PubMedDate not supplied

Hemodynamic and vascular permeability effects of lipid emulsion in the isolated canine lung lobe.

The isolated canine right lower lung lobe (RLL) perfused with autogenous blood at constant flow was used to study the effects of a parenteral lipid emulsion, Liposyn 10%, on pulmonary hemodynamics and vascular permeability. Lobes were placed into four groups: (1) control lobes (C; n = 6), which were infused via the lobar artery with normal saline at 1 ml.min-1 for 30 min; (2) lipid emulsion lobes (L; n = 6), which were infused via the lobar artery with Liposyn 10% at 1 ml.min-1 for 15 min; (3) lobes infused with both Liposyn 10% and 0.25 to 6.0 mg of lipoprotein lipase (LL; n = 4); and (4) lobes infused with 0.13 to 6.0 mg of lipoprotein lipase alone (LP; n = 6). Liposyn infusion alone caused no changes in lobar hemodynamics compared to group C. Over time there were no differences between groups C and L on venous PO2, PCO2, or pH. Post-infusion weight gain (over 10 to 14 min) averaged 0.23 +/- 0.08, 0.19 +/- 0.07, 0.66 +/- 0.23, and 3.00 +/- 1.46 g.min-1.100 g-1 RLL for groups C, L, LP, and LL, respectively (p less than 0.05, for group LL compared to Group C). The pulmonary filtration coefficient (Kf) was determined as an index of vascular permeability. Groups C and L had Kf values of 0.07 +/- 0.01 and 0.28 +/- 0.22 ml.min-1.mm Hg-1.100 g-1 (mean +/- SE), respectively, which did not differ significantly (p greater than 0.05). Liposyn 10%, given in a concentration larger than that used clinically, produced no untoward pulmonary vascular effects.(ABSTRACT TRUNCATED AT 250 WORDS)

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