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Biomedical subjects

L Volicer

Publications and source records attributed to L Volicer.

At least 127 records · Page 7Linked to original sources
PubMed1978

Effect of histamine on cyclic AMP levels in control and antigen-sensitized guinea pig lungs.

The effect of histamine on cyclic AMP was investigated in control and antigen-sensitized guinea pig lungs. Although histamine elevated the cyclic AMP levels in a dose-dependent manner in both groups, the response was consistently smaller in the sensitized lungs. In vivo pretreatment of control guinea pigs with histamine decreased the subsequent effect of exogenous histamine on cyclic AMP. Phosphodiesterase activity was not different in the two groups and it was not affected by histamine. These results indicate that the process of antigen sensitization results in an altered cyclic AMP response to histamine.

Animals↗
PubMed1977

Norepinephrine uptake in guinea pig lung. Effects of anaphylaxis, phenoxybenzamine and cocaine.

Lungs from control and sensitized guinea pigs were perfused via the pulmonary artery with Tyrode's solution. Infusion of equimolar concentrations (3x10(-9) to 3x10(-6 M) of 3H-1-norepinephrine (NE) and 14C-urea was started 1 min after injection of 1 ml 0.9% NaCl or 50 mg ovalbumin in 1 ml 0.9% NaCl and continued for 15 min. Anaphylactic lungs retained more urea, NE, and NE metabolites than control lungs at all NE concentrations and the proportion of unchanged NE was higher. Phenoxybenzamine decreased the 3H/14C ratio due to decreased 3H accumulation. Cocaine affected predominantly the control lungs. The results indicate that anaphylaxis increased the net uptake of NE in the lung and decreased the metabolism of retained NE.

Anaphylaxis↗
PubMed1977

Effect of ethanol on the cyclic AMP system in rat brain.

The effects of ethanol on adenylate cyclase and phosphodiesterase activity in vitro, and on cyclic AMP, ATP and adenosine levels in vivo were studied. Ethanol appeared to affect the cyclic AMP system indirectly, probably through its effect on neurotransmitter release or on adenosine formation.

Adenosine↗
PubMed1977

Effects of acute and chronic ethanol administration and withdrawal on adenosine 3':5'-monophosphate and guanosine 3':5'-monophosphate levels in the rat brain.

The effect of ethanol on cyclic nucleotide levels was investigated in male Sprague-Dawley rats. The rats were sacrificed by microwave irradiation, the brains were divided into four areas, and cyclic nucleotides were measured by radioimmunoassays. Administration of a single dose of ethanol per os produced a dose-dependent decrease of adenosine 3':5'-monophosphate (cyclic AMP) in cerebral cortex, cerebellum, pons and medulla oblongata while guanosine 3':5'-monophosphate (cyclic GMP) was decreased in all brain areas. Dependence on ethanol was induced by three daily administrations of ethanol p.o. for 7 days. The last dose of ethanol did not produce any decrease of cyclic AMP levels while the decrease of cyclic GMP levels was still present. During ethanol withdrawal cyclic AMP levels increased in cerebral cortex, pons and medulla oblongata and did not change in cerebellum. Changes of cyclic AMP in subcortex were more complex. Cyclic GMP levels increased during ethanol withdrawal in cerebellum, pons and medulla oblongata and did not change in cerebral cortex and subcortex. These results indicate that changes of cyclic nucleotides might participate in the mechanism of ethanol dependence and withdrawal.

Animals↗
PubMed1977

Use of propranolol in the treatment of idiopathic orthostatic hypotension.

Five patients with idiopathic orthostatic hypotension who had physiologic and biochemical evidence of severe autonomic dysfunction were included in the study. They all exhibited markedly reduced plasma catecholamines and plasma renin activity in both recumbent and upright positions and had marked hypersensitivity to the pressor effects of infused norepinephrine. Treatment with propanolol administered intravenously (1-5 mg) produced increases in supine and upright blood pressure in 4 of the 5 individuals with rises ranging from 11/6 to 22/11 mmHg. Chronic oral administration of propranolol (40-160 mg/day) also elevated the blood pressures of these individuals with increases in the order of 20-35/15-25 mmg being observed. In 1 patient, marked hypertension was induced by propranolol and the drug had to be withdrawn. It otherwise was well tolerated and no important side effects were observed. Treatment has been continued in 3 individuals for 6-13 months with persistence of the pressor effect, although there appears to have been some decrease in the degree of response with time. Hemodynamic measurements in 1 of the patients demonstrated an increase in total peripheral resistance and essentially no change in cardiac output following propranolol therapy. The studies suggest that propranolol is a useful drug in selected patients with severe idiopathic orthostatic hypotension.

Aged↗
PubMed1976

Effect of epinephrine on cyclic AMP levels and adenylate cyclase and phosphodiesterase activities in control and antigen-sensitized guinea pig lungs.

Cyclic AMP levels and adenylate cyclase and phosphodiesterase activities were measured in control and ovalbumin-sensitized guinea pig lungs. Cyclic AMP levels were raised by epinephrine (0.01-10 mug/ml) in both control and sensitized lungs; the response being larger in the former group. Epinephrine (10(-9) -10(-6) M) stimulated adenylate cyclase in sensitized but had only a minimal effect in control preparations. Phosphodiesterase activities were equal in both groups. The hypersensitivity of adenylate cyclase response to epinephrine concurrent with diminished accumulation of cyclic AMP in sensitized guinea pigs indicate that antigen sensitization alters the response of the cyclic AMP system to epinephrine.

Adenylyl Cyclases↗
PubMed1976

Adenylate cyclase activity in heart and lung: effect of epinephrine and histamine in control and sensitized guinea pigs.

The effect of epinephrine and histamine on adenylate cyclase activity in lungs and hearts of control and ovalbumin-sensitized guinea pigs was investigated. Epinephrine at 10(-6) M concentration stimulated adenylate cyclase from both organs of the sensitized animals but had no effect on the enzyme from control tissues. At 10(-4) M, epinephrine stimulated equally the enzyme activity from the control and sensitized lungs and hearts. Histamine, 10(-6) and 10(-4), stimulated equally adenylate cyclase in tissues from both groups of animals. The results suggest that ovalbumin sensitization leads to hypersensitivity of the beta-adrenergic receptors to epinephrine without changing their sensitivity to histamine.

Adenylyl Cyclases↗