Catecholamine Transport in Isolated Lung Parenchyma of Pig

Abstract

Normetanephrine (80upM) and 3-0-methylisoprenaline (50pM), which also depressed the accumulation of cellular radioactivitv from [3H]-Iso by > 50%, caused rightward shifts in Iso concentrationeffect curves as a result of P-adrenoceptor blockade. In sharp contrast, cortisol (80 AM) and U-0521 (60 MM), which caused smaller reductions in the cellular accumulation of radioactivity derived from [3H]-Iso, both caused an approximately 9 fold potentiation of responses to Iso in isolated lung strips. 5 The results indicate that the major sites of uptake andmetabolism of NA in porcine parenchyma strip are remote from a-adrenoceptors mediating NA-induced contraction. Similarly, some major sites of uptake of Iso are remote from P-adrenoceptors mediating Iso-induced relaxation. However, P-adrenoceptors are apparently in close proximity to a compartment containing COMT activity.

Classification of β‐adrenoceptors in isolated bronchus of the pig

“…Thus phentolamineinduced increases in the potency of catecholamines were probably due to inhibition of uptake processes (Foster, 1967;1968;1969;Goldie & Paterson, 1982) rather than to inhibition of post-synaptic aadrenoceptors. Similarly, it is unlikely that the 12.3 % reduction in carbachol-induced tone produced by phentolamine (15 jAM) contributed markedly to increased amine potency since Iso potency was only increased 1.3 fold when the concentration of carbachol used to pre-contract bronchi was reduced by 50%.…”

“…Neuronal uptake does not appear to alter the potency of catecholamines in pig bronchus. While inhibition of extraneuronal uptake with normetanephrine (50 gM) only caused a 2 fold increase in the potency of Iso, it is possible that 1-adrenoceptor blockade caused by normetanephrine partially masked sensitization to Iso (Kenakin, 1980;Goldie & Paterson, 1982 In guinea-pig atria where a homogeneous population of 1l-adrenoceptors also exists (O'Donnell & Wanstall, 1979a,b), the pA2 value for atenolol against Iso was also 7.2 (Harms, 1976). In contrast, in the pig lung parenchyma strip where P2-adrenoceptors predominate, the pA2 value for atenolol against Iso was only 5.4 (Goldie et aL, 1982a).…”

“…Concentration-effect curves to two of the other amines were constructed in turn. In some experiments, after the first two control curves were established, a third curve was constructed to the same amine in the presence of normetanephrine (50 luM) to determine the effect of inhibiting extraneuronal uptake, or in the presence of phentolamine (15 A1M) which inhibits both a-adrenoceptors and catecholamine uptake processes (Foster, 1967;1968;1969;Goldie & Paterson, 1982). Concentration-effect curves to Iso were also established in the absence and presence of a competitive P-adrenoceptor antagonist and pA2 values established by the method of Arunlakshana & Schild (1959).…”

Effect of respiratory tract viral infection on murine airway β‐adrenoceptor function, distribution and density

“…Another 2 concentration-effect curves to the relaxants were subsequently constructed in each preparation. Cocaine (10puM) and 10pM phentolamine were added to the bath 30min before the start of all concentration-effect curves to inhibit a-adrenoceptors and neuronal and extraneuronal uptake systems (Goldie & Paterson, 1982 …”

A Comparative Study of Β‐adrenoceptors in Human and Porcine Lung Parenchyma Strip

“…Preparations were left to equilibrate for 60-90min with regular washing before any druginduced effects were measured. Unless otherwise stated, tissues were exposed to phentolamine (15 piM) i The Macmillan Press Ltd 1982 for the duration of experiments to inhibit aadrenoceptors and catecholamine uptake processes (Foster, 1968;1969;Goldie & Paterson, 1982).…”