Rolipram inhibits airway microvascular leakage induced by platelet-activating factor,histamine and bradykinin in guinea-pigs

Abstract— Rolipram (0·1–1000 μg kg^?1, i.v.) reduced the increase in microvascular permeability induced by platelet-activating factor (PAF; 50 ng kg^?1, i.v.) at different sites of the guinea-pig airways. Rolipram (1–100μg kg^?1, i.v.) inhibited histamine (30μg kg^?1, i.v.)-and bradykinin (0·3 μg kg, i.v.)-induced airway microvascular leakage. These effects of rolipram were obtained at doses which inhibit histamine (7–20 μg kg^?1 min^?1)-induced bronchoconstriction (IC50 = 3 ± 1 μg kg, i.v.) without depressing arterial blood pressure in the guinea-pig. Aminophylline (50 mg kg^?1) did not change the effect of PAF. The anti-exudative effect of rolipram is of potential therapeutic value in asthma.     

Recovery Curve and Concealed Conduction in the His-Purkinje System of the Rabbit Heart: Effects of Radiofrequency Modification of the Low AV Junction

The aim of this study was to analyze the recovery curve and concealed conduction in the normal His-Purkinje system and after delivering radiofrequency current in the low AV junction, in the perfused rabbit heart. Twenty-one rabbit hearts were studied. Radiofrequency current (5 W) was delivered in the low AV junction to induce an incomplete His-Purkinje AV block (HV prolongation with 1:1 AV conduction); this was achieved in 9 experiments (Croup I), while 12 experiments developed a complete block (Group II). Atrial stimulation was performed in both Groups at baseline, and in Group Softer radiofrequency delivery, as follows: (1) pacing at increasing rates to determine the His-Purkinje AV block cycle length; (2) atrial extrastimulus test (A₁ A₂)J to calculate the His-Purkinje effective refractory period and the fitting of the recovery curve (H₁H₂ vs H₁V₂) to the exponential equation ΔHV=a.e^-b.(H1H2);(3) concealed conduction protocol (in 15 experiments) consisting of an atrial extrastimulus test with an interposed beat (A₁-A₀-A₂) at a fixed A₁A₂ coupling interval. The baseline recovery curve fitted an exponential equation in 17 experiments (with a 93%± 42% maximum H₂V₂ increase at the shortest H₁H₂), but did not in 4 experiments (the maximum H₂V₂ increase being only 22%± 7%). Radiofrequency application prolonged the HV interval (25 ± 6 ms vs 46 ± 16 ms: P = 0.001) and His-Purkinje effective refractory period (167 ± 28 ms vs 217 ± 57 ms; P = 0.02). The percentage increment was greater for HV than for refractory period (99%± 65% vs 35%± 32%; P = 0.02); however, the increment of the His-Purkinje block cycle length (77%± 74%) only correlated with that of the refractory period (r = 0.95; P = 0.0001). The recovery curve after radiofrequency delivery fitted an exponential equation in all experiments, showing a rightward shift expressed by an increment of the constant In a (2.7 ± 1.9 vs 5.5 ± 5.5; P = 0.02). Concealed conduction appeared in only three experiments at baseline. After radiofrequency, however, it was observed in all experiments, producing a rightward shift of the recovery curve and an In a increase (2.87 ± 1.2 vs 9.9 ± 2.7; P = 0.0001). When H₀ was conducted, the curve rightward shift and In a increase (26 ± 7.5; P = 0.0001) were greater. Conclusions: (1) His-Purkinje physiology, as in A V nodal physiology, can be described by a recovery curve that fits an exponential equation, especially if conduction becomes depressed with radiofrequency current. (2) Radiofrequency application in the low AV junction modifies His-Purkinje conduction more than refractoriness, though the refractoriness increase determines the degree of block at fast atrial rates. (3) Concealed conduction is uncommon in the normal His-Purkinje system during atrial pacing, but very frequent after modifying the low AV junction with radiofrequency current.     

Retrograde P wave polarity in reciprocating tachycardia utilizing lateral bypass tracts

Electrophysiological study of 26 patients with paroxysmal supraventriculartachycardia showed that the tachycardias were due to a circusmovement using a lateral atrioventricular bypass tract as aretrograde limb of the circuit. The Wolff-Parkinson-White syndromewas overt in 19 cases and concealed in the remaining seven. Retrograde P wave polarity and morphology during tachycardiawere studied and related to the location of the bypass tracton the left or right side of the heart. In all cases the P waveduring tachycardia was located after the QRS complex. Of 19cases with left bypass tract, the retrograde P wave in leadI was negative in 14, diphasic (–.+) in four, and indeterminatein one case. In lead V, the P wave was positive in 16 casesand indeterminate in three. Of seven cases with right bypasstract, the retrograde P wave in lead I was positive and bimodalin six cases and indeterminate in the remaining case, whileit was negative and bimodal in lead V₁ in all but one case. Hence, it may be concluded that analysis of retrograde P wavemorphology during tachycardia, together with other electrocardiographsfactors, can be useful in determining the type of circuit usedin reciprocating tachycardia.     

The innervation of rainbow trout (Oncorhynchus mykiss) liver: protein gene product 9.5 and neuronal nitric oxide synthase immunoreactivities

We have explored the innervation of the rainbow trout ( O. mykiss ) liver using immunohistochemical procedures and light microscopy to detect in situ protein gene product 9.5 and neuronal nitric oxide synthase immunoreactivities (PGP-IR and NOS-IR). The results showed PGP-IR nerve fibres running with the extralobular biliary duct (EBD), hepatic artery (EHA) and portal vein (EPV) that form the hepatic hilum, as well as following the spatial distribution of the intrahepatic blood vessel and biliary channels. These nerve fibres appear as single varicose processes, thin bundles, or thick bundles depending on their diameter and location in the wall of the blood vessel or biliary duct. No PGP-IR fibres were detected in the liver parenchyma. NOS-IR nerve fibres were located only in the vessels and ducts that form the hepatic hilum (EBD, EHA, EPV); in addition, NOS-IR nerve cell bodies were found isolated or forming ganglionated plexuses in the peribiliary fibromuscular tissue of the EBD. No PGP-IR ganglionated plexuses were detected in the EBD. The location of the general (PGP-IR) and nitrergic (nNOS-IR) intrinsic nerves of the trout liver suggest a conserved evolutionary role of the nervous control of hepatic blood flow and hepatobiliary activity.