Influence of oxygen deficiency and vasodilating drugs on coronary arterial tonus was investigated. In the fibrillating heart, hypoxia initially decreased total coronary resistance, later increased it, and exerted little effect on large coronary arteries. Dilation of helically cut specimens of the small coronary arteries occurred more readily than observed in large arteries in response to N2 bubbling or KCN. In the small arteries, the mitochondrial population was more numerous in cellular units and succinic dehydrogenase activity was greater, suggesting that these vessels are more dependent on aerobic metabolism for the maintenance of integrity. Nitrate vasodilators relaxed selectively the large arteries, while adenosine, prenylamine and carbochromen dilated preferentially the small arteries. Dipyridamole, iproveratril, papaverine and propranolol relaxed both arteries equally; however, except for propranolol, these drugs produced preferential relaxation of the small vessels in the fibrillating hearts.

Adenosine↗

PubMedDate not supplied

Abnormal myocardial uptake and clearance of 123I-labeled metaiodobenzylguanidine in patients with chronic renal failure and autonomic dysfunction.

BACKGROUND: Patients with chronic renal failure were evaluated with 123I-labeled metaiodobenzylguanidine (MIBG) myocardial scintigraphy to investigate the relationship between abnormal findings on MIBG scintigrams and autonomic dysfunction. METHODS AND RESULTS: Eleven control subjects and 20 patients with chronic renal failure (CRF) (serum creatinine level > 8 mg/dl) were evaluated by MIBG myocardial scintigraphy and power spectral analysis (PSA) of the R-R fluctuations of the electrocardiogram. Subjects with CRF were divided into two groups: without (CRF1; nine patients) or with (CRF2; 11 patients) autonomic neuropathy. From MIBG images, the heart/mediastinum mean count rate, defect score, which was scored visually, and clearance rate were calculated. Percent low-frequency power and high-frequency power were obtained from PSA. MIBG scintigrams showed decreased heart/mediastinum mean count rate, a high defect score in both initial and delayed images, and rapid clearance rate in the CRF2 group. PSA showed an abnormally low percent low-frequency power and high-frequency power in the CRF2 group. In addition, there was a weak but significant inverse correlation between percent low-frequency power and defect score. CONCLUSION: Alterations in MIBG scintigrams are seen in patients with autonomic dysfunction in CRF and may be useful for evaluating cardiac sympathetic dysfunction in those patients.

3-Iodobenzylguanidine↗

PubMedDate not supplied

Autocytotoxic activity of lymphokine-activated killer cells: characterization of effector cells and susceptible targets.

The specificities and surface markers of murine autocytotoxic cells induced by in vitro culture with interleukin 2 (IL2) were studied. Culturing murine spleen cells with recombinant human IL2 resulted in the generation of cytotoxic cells which killed syngeneic lymphoblasts and syngeneic activated macrophages (M phi). Both lectins and protein antigens were capable of inducing lymphoblasts recognized by lymphokine-activated killer (LAK) cells. B-lymphoblasts as well as T-lymphoblasts were sensitive to lysis by these effector cells. In addition, peritoneal M phi activated in vivo with Bacille Calmette-Guérin (BCB), Corynebacterium parvum (C. parvum), thioglycollate (TG) or lipopolysaccharide (LPS) were shown to be susceptible to lysis by LAK cells. In contrast, neither unstimulated T cells nor resident peritoneal M phi were sensitive to lysis by LAK cells, suggesting that normal cells have to be activated in order to be sensitive to lysis by these effector cells. Surface marker analysis indicated that majority of effector cells which killed syngeneic lymphoblasts and activated M phi were Thy1+, asialo GM1+, L3T4-, Ly2-.

Animals↗