Protamine sulfate causes pulmonary hypertension and edema in isolated rat lungs

The polycation protamine sulfate increases microvascular permeability in the kidney by reducing glomerular charge. We have exposed the pulmonary vasculature to protamine sulfate to determine whether electrical charges play a role in protein permeability in lung vascular beds. In anephric rats, protamine sulfate increased hematocrit approximately 25%. With protamine sulfate doses of 0.08 and 0.04 mg/g body wt, lung blood-free wet-to-dry weight ratios were increased (5.24 +/- 0.8 and 4.89 +/- 0.7) compared with control (3.85 +/- 0.3) (P less than 0.05). In isolated, ventilated, and perfused lungs 0.04 mg/g body wt protamine sulfate increased pulmonary arterial pressure from 5.2 +/- 1.4 to 16.3 +/- 3.9 mmHg (P less than 0.01). These lungs gained weight and lung wet-to-dry weight ratios were significantly increased (15.33 +/- 4.26 compared with 6.04 +/- 0.24 for control lungs). Poly-L-lysine, another polycation, also caused significant increases in pulmonary arterial pressure, lung weight, and lung wet-to-dry weight ratios. The addition of diphenhydramine to the perfusate 10 min before the addition of protamine sulfate did not prevent these changes. Heparin (90 U/mg protamine sulfate) reversed the abnormalities. Pulmonary arterial pressure (7.0 +/- 1.1 mmHg) was not significantly different from the control value, lung weight did not increase, and the lung wet-to-dry weight ratio was 6.24 +/- 0.23 (P greater than 0.05). We conclude that polycations have a significant effect on pulmonary vascular resistance and perhaps on permeability.     

Structural analysis of covalently labeled estrogen receptors by limited proteolysis and monoclonal antibody reactivity

We have used limited proteolysis of affinity-labeled estrogen receptors (ER), coupled with antireceptor antibody immunoreactivity, to assess structural features of ER and the relatedness of ER from MCF-7 human breast cancer and rat uterine cells. MCF-7 ER preparations covalently labeled with [3H]tamoxifen aziridine [( 3H]TAZ) were treated with trypsin (T), alpha-chymotrypsin (C), or Staphylococcus aureus V8 protease prior to electrophoresis on sodium dodecyl sulfate gels. Fluorography revealed a distinctive ladder of ER fragments containing TAZ for each protease generated from the Mr 66,000 ER: for T, fragments of 50K, 38K, 36K, 31K, 29K, and 28K that with longer exposure generated a 6K fragment; for C, fragments of 50K, 38K, 35K, 33K, 31K, 19K, and 18K that with longer exposure generated 14K and 6K fragments; and for V8, ca. 10 fragments between 62K and 28K. Two-dimensional gels revealed charge heterogeneity (two to three spots between pI 5.5 and 6.2) of the 66K ER and the T-generated 28K meroreceptor form. Immunoblot detection with the primate-specific antibody D75P3 gamma revealed that all immunoreactive fragments corresponded to TAZ-labeled fragments but that some small TAZ-labeled fragments (V8-generated forms less than 47K and T-generated forms less than 31K) were no longer immunoreactive. In contrast, use of the antibody H222Sp gamma revealed a correspondence between TAZ-labeled and immunoreactive fragments down to the smallest fragments generated, ca. 6K for T and C and 28K for V8. MCF-7 nuclear and cytosol ER showed very similar digest patterns, and there was a remarkable similarity in the TAZ-labeled and H222-immunoreactive fragments generated by proteolysis of both MCF-7 and rat uterine ER. These findings reveal great structural similarities between the human (breast cancer) and rat (uterine) ER and between nuclear and cytosol ER, indicate charge heterogeneity of ER, and allow a comparison of the immunoreactive and hormone attachment site domains of the ER. The observation that T and C generate a ca. 6K TAZ-labeled fragment that is also detectable with the H222 antibody should be of interest in studies determining the hormone binding domain of the ER and in amino acid sequencing of this region.     

Adaptation of the tetrazolium method for testing the seed viability, and scanning electron microscopy study of some Western European orchids

A modified tetrazolium method was formulated for use with seeds of Western European orchids. The sequence of treatments which gave the highest percentage of coloured (i.e. viable) embryos was: (1) pretreatment in a solution of 5% (w/v) Ca(OCl)₂+ 1% (v/v) Tween-80, (2) soaking for 1 day in sterile water, (3) the classical tetrazolium test. The optimal duration of the pretreatment in Ca(OCl)₂+ Tween-80 depends upon the species, and to investigate the effect a scanning electron microscopy study was performed on the testa of 3 species. For a given species, the optimal pretreatment period was not affected by the year of harvest or the source of the seed lots.     

Topography of the C terminus of cytochrome b5 tightly bound to dimyristoylphosphatidylcholine vesicles

Cytochrome b5 holoenzyme was bound asymmetrically in the tightly bound form to small unilamellar dimyristoylphosphatidylcholine vesicles. [3H]Taurine, a membrane-impermeant nucleophile, was added to the external medium and was then cross-linked to cytochrome carboxyl residues by the addition of a water-soluble carbodiimide. Nonpolar peptide was isolated after trypsin digestion of taurine-labeled apocytochrome b5 and contained 1.7-1.9 residues of taurine. The C-terminal tetrapeptide containing residues Thr130-Asn133 was generated by chymotryptic hydrolysis of radiolabeled nonpolar peptide and was purified by gel filtration and ion exchange chromatography. Amino acid analysis of the C-terminal tetrapeptide showed that about 1.6 mol of taurine was cross-linked per mol of peptide. When the experiment was performed with taurine trapped inside the vesicles, no cross-linking was observed. The results suggest that when cytochrome b5 holoenzyme is bound to vesicles in the tight binding form, the C terminus is located on the external surface of the vesicles.     

Parathyroid hormone stimulates adenylate cyclase in rat cerebral microvessels

We have studied the effect of parathyroid hormone (PTH) on adenylate cyclase of microvessels isolated from rat cerebral cortex. Native bovine (b) PTH-(1–84), the synthetic amino-terminal fragment bPTH-(1–34) and the synthetic analog [Nle⁸, Nle¹⁸, Tyr³⁴]-bPTH- (1–34) amide stimulated adenylate cyclase in a dose-dependent manner with apparent ED₅₀ values of 16 nM, 6.3 nM and 15 nM respectively. The stimulation by bPTH was greatly enhanced by guanosine triphosphate. The PTH antagonist, [Nle⁸, Nle¹⁸, Tyr³⁴]-bPTH-(3–34) amide inhibited the action of bPTH-(1–84) and bPTH-(1–34). In summary, PTH stimulated adenylate cyclase in rat cerebral microvessels in a very similar manner to its stimulation in the renal cortex.