Radical splenopancreatectomy with duodenal loop conservation in rats.

In an attempt to find a reproducible method of total splenopancreatectomy (TSP) with duodenal loop conservation in rats, we used the technique recently described by S. Houry and M. Huguier (Eur. Surg. Res. 15: 328, 1983) but were not able to induce a true diabetes. We therefore developed a more radical splenopancreatectomy (RSP) in rats and compared this technique with the TSP. RSP involves a more extensive dissection of the common bile duct, a short choledocoduodenal anastomosis, and total excision of the retroportal pancreatic lobules with the aid of a dissecting microscope. In rats who had undergone the TSP technique, blood glucose levels were maximal 8 hr after operation (270 +/- 16 mg/dl), and thereafter recovered baseline values. In contrast, after the RSP technique all the rats became diabetic as documented by persistent hyperglycemia (347 +/- 20 mg/dl at 8 hr, P = 0.01 compared to TSP; 500 +/- 20 mg/dl at 8 hr, P less than 0.0001). Eight hours after the operation, blood lipase levels increased more significantly after TSP than after RSP (847 +/- 247 IU/liter and 130 +/- 37 IU/liter, respectively, P = 0.01), and then decreased to 92 +/- 19 IU/liter at 24 hr in the TSP group and less than or equal to 30 IU/liter in the RSP group (P = 0.003), suggesting a more radical dissection of pancreatic tissue with the RSP technique. At sacrifice at 48 hr, no complications were found with either technique on macroscopic and microscopic examination, except for marked gastric distension with RSP. A third group of rats underwent RSP and were followed until natural death.(ABSTRACT TRUNCATED AT 250 WORDS)

Adverse cardiopulmonary effects and increased plasma thromboxane concentrations following the neutralization of heparin with protamine in awake sheep are infusion rate-dependent.

The effect of the rate of intravenous infusion of protamine on the acute hemodynamic and pulmonary effects of heparin neutralization was investigated in six adult sheep surgically instrumented for chronic studies. Bovine lung heparin at a dose of 200 IU/kg was injected intravenously over 10 sec, 5 min before the start of protamine administration. On separate experimental days, each sheep received protamine at the same dose of 2 mg/kg, but it was infused over four different time periods: 3 s, 30 s, 300 s, or 30 min. At an additional session, protamine was administered over 3 s without prior heparinization to assess the effect of protamine alone. The sequence of the sessions was randomized and performed blindly. Injecting protamine in unheparinized sheep produced no change in any of the measured variables. In contrast, when protamine was injected over 3 s in heparinized sheep, it induced a transient and significant (P less than 0.001) pulmonary hypertension (from 17.2 +/- 1.5 to 45.6 +/- 2.4 mmHg at 1 min) with an increased pulmonary (five-fold) and systemic (2.5-fold) vascular resistance; a decrease of cardiac output (from 3.85 +/- 0.43 to 1.93 +/- 0.29 l/min) without change in left atrial pressure (from 5.3 +/- 1.3 to 6.0 +/- 1.7 mmHg; P = NS); a significant (P less than 0.001) increase of plasma thromboxane B2 (TxB2) concentrations (from 349 +/- 131 to 974 +/- 218 pg/ml); leukopenia (76 +/- 4% of baseline white blood cell counts); and hypoxemia (PaO2 decreased from 81 +/- 3 to 63 +/- 4 mmHg at 2 min). Administering the same amount of protamine after heparin at a slower infusion rate significantly attenuated and delayed all components of the adverse response to protamine. This attenuation occurred in an infusion rate-dependent fashion, so that when protamine was infused over 30 min, no significant changes in any of the measured variables were noted. The time course of plasma heparin concentrations following protamine indicated that chemical heparin was completely neutralized over the time period of protamine infusion. These results demonstrate that the rate of generation of heparin-protamine complexes (as detected by changes of plasma concentrations of chemical heparin) during iv protamine infusion started 5 min after heparin administration is a factor involved in the generation of sufficient mediators required to initiate a characteristic physiologic response in sheep, including systemic and pulmonary vasoconstriction, TxB2 generation, and leukopenia. Infusing a neutralizing dose of protamine over 30 min avoids these adverse reactions in sheep.

Bleomycin primes monocytes-macrophages for superoxide production.

Bleomycin (BLM) induces lung inflammation and subsequent fibrosis in humans and animal models. We hypothesized that monocytes-macrophages represent target cells for BLM toxicity and participate in the initial stages of pulmonary inflammation. We developed an animal model of early lung lesions using systemic administration of BLM (2 U.100 g-1 body weight over 5 days) (BLM-rats). We observed a significant decrease in body weight and in serum angiotensin converting enzyme activity in BLM-rats as compared to matched controls rats, but no evidence of fibrosis was seen in optic microscopy of the lungs from BLM-rats. In contrast, electron microscopy revealed accumulation of intracapillary polymorphonuclear leucocytes and unusual presence of eosinophils. We then investigated the in vivo effects of BLM on the respiratory burst of monocytes-macrophages. As compared to control rats, production of superoxide (O2-) by alveolar macrophages from BLM-rats was increased upon stimulation with either phorbol myristate acetate (21.04 +/- 2.78 versus 11.45 +/- 2.26 nmol.10(6) cells.20 min-1, p less than 0.05) or opsonized zymosan (9.35 +/- 0.87 versus 7.03 +/- 0.66 nmol.10(6) cells.20 min-1, p less than 0.05). We also found in BLM-rats an increased number of circulating monocytes and an increased production of O2- by these cells. Monocytes-macrophages may represent a target cell in the early events of BLM toxicity in vivo and the increased production of O2- by these cells participates in tissue injury in pulmonary fibrosis.

Lung uptake of 131I-metaiodobenzylguanidine in sheep. An in vivo measurement of pulmonary metabolic function.

Circulating biogenic amines are known to be cleared by the mammalian lung. Their lung uptake is considered as an indicator of pulmonary endothelial integrity. Unfortunately, their use as markers of pulmonary metabolic function in human pathology is precluded by their biological effects and by the type of radiolabeling (3H and 14C), making them harmful for repeat injections and unfit for scintigraphy. Metaiodobenzylguanidine (MIBG) is structurally related to the neuron blocking agent guanethidine, devoid of significant biological effects, and has been shown to be extracted by the same active sodium dependent, saturable transport as norepinephrine in perfused rat lungs in vitro. We studied the single pass lung extraction of 131I-MIBG in five awake and five anaesthetised sheep using the standard double indicator dilution technique with 99mTc-human serum albumin (HSA) as an intravascular reference tracer. Intravenous bolus injection of increasing doses of MIBG up to 400 nmol resulted in a significant (F ratio = 7.778, P less than 0.0001) dose dependent decrease of MIBG extraction in both awake and anaesthetised sheep, without significant differences of extraction values between the two groups. For the 10 sheep, the averaged percentage single pass pulmonary uptake of MIBG at the peak of the dilution curve decreased from 32% +/- 3% (mean +/- SE, n = 27 measurements) with 20 nmol to 18% +/- 2% (n = 32) with 400 nmol. Estimates of the apparent Michaelis-Menten constant (Km) averaged 2 +/- 1.2 microM (n = 7), whereas estimates of the apparent maximum velocity of removal (Vmax) was 1.1 +/- 0.5 mumol/min (n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)

Volume, surface, and junctions of rat aortic endothelium during experimental hypertension: a morphometric and freeze fracture study.

Three models of hypertension were induced in Wistar rats: (1) aortic ligature between renal arteries, (2) uninephrectomy and Na-rich diet, (3) uninephrectomy, 0.9 per cent NaCl as drinking fluid and subcutaneous administration of desoxicorticosterone acetate (DOCA). We studied in aortic endothelium during the early (7 to 10 days) and late (40 days) phases of these models: (1) volume, surface, and ratios of tight and gap junctions to lateral membrane surface by means of morphometric analysis using thin-sectioning electron microscopy, and (2) organization of tight and gap junctions by means of freeze fracture electron microscopy. Compared with normotensive rats: (1) volume of the endothelial cell layer was increased in all hypertensive situations with the exception of the late group after aortic ligature; the increase was most marked early after aortic ligature and early and late after DOCA; (2) endothelial surface to volume ratio was markedly decreased early after aortic ligature and early and late after DOCA; the ratio of luminal, abluminal, and lateral to total endothelial surface remained unchanged in all hypertensive situations; (3) in all hypertensive situations the ratio of tight junctions to lateral membrane surface increased, whereas the ratio of gap junctions to lateral membrane surface showed no significant change; (4) in all hypertensive situations lateral endothelial plasma membranes contained, in addition to zonular and macular type tight junctions, many small aggregates of intramembrane particles in the P face and particle-free grooves in the E face; these structures were particularly numerous early after aortic ligature and early and late after DOCA; (5) in all hypertensive situations (most early and late after DOCA and least after sodium-rich diet) gap junctions were irregularly shaped in contrast to those of normotensive animals. Our results suggest that : (1) different types of hypertension produced different degrees of hypertrophy of the endothelial cell layer ; (2) hypertension increases the ratio of tight junctions to lateral endothelial membrane surface; the presence of small aggregates of intramembrane particles (probably representing assembly and/or disassembly of tight junctions) in the lateral endothelial plasma membranes is responsible for this phenomenon; (3) hypertension does not change the ratio of gap junctions to lateral membrane surface but results in abnormal gap junction morphology.

Distribution and function of cytoskeletal proteins in lung cells with particular reference to 'contractile interstitial cells'.

Cytoskeletal proteins are demonstrated in the interstitial cells of the lungs. These proteins appear in the cytoplasm as bundles of microfilaments, the individual filaments measuring 40--80 A in diameter. The presence of actin and myosin in these cells is demonstrated by immunofluorescence. Antiactin antibodies (AAA) obtained from patients with chronic aggressive hepatitis, as well as AAA and antimyosin antibodies prepared in the rabbit, are used. The major difference between the cytoskeletal proteins of interstitial cells and other cells of the alveolar tissue (type II epithelium, pericytes, and near the junctional complexes of endothelial cells) is that the microfilaments within the interstitial cells are organized into bundles forming tiny intracytoplasmic 'muscles'. Furthermore, they appear to be much more abundant and seem to anchor the cell on the alveolar basement membrane by hemidesmosome-like structures. These peculiar cytological features provide these cells with an important functional capacity. Being located in the 'pillars' which cross the capillary space, the contraction of interstitial cells may modify the alveolocapillary configuration in some circumstances. The physiological importance of such an 'active' alveolar motility is to provide the lung with a mechanism of autoregulation of the ventilation/perfusion (V/Q) ratio at alveolar level.