Carbonic anhydrases

Expression and quantitative changes of carbonic anhydrase in developing neurones of rat central nervous system

Postnatal changes in carbonic anhydrase activity were investigated in the islands of Calleja, which have been previously reported to contain the enzyme. Results obtained with a new modified method of Hansson provided further evidence for the distinction between the medial and lateral islands of Calleja. The enzyme was localized mainly in the nucleus and cytoplasm of granule cells without showing binding to any cytoplasmic organelle. No large neurons of the islands displayed carbonic anhydrase reactivity. The time course and rate of increase of carbonic anhydrase expression were different in the giant island of Calleja and lateral islands and this finding may strengthen the hypothesis regarding the medio-lateral diversity of Calleja's islands. On the other hand, at the end of the maturation process the granule cell complexes showed no significant difference in the proportion of carbonic anhydrase positive neurones. The almost equal rate of appearance of carbonic anhydrase reactive granule cells raises the possibility of a basic common role of both medial and lateral islets.

IgM natural autoantibodies against bromelain-treated mouse red blood cells recognise carbonic anhydrase

Carbonic anhydrase (CA) from mouse erythrocyte membranes is recognised as an autoantigen in Western blotting experiments with FUB 1, a murine IgM monoclonal antibody that binds both phosphatidylcholine and bromelain-treated mouse red blood cells (BrMRBC). Serum from mice stimulated with lipopolysaccharide (LPS-serum) also recognises CA. From SDS-PAGE, and blotting experiments with whole mouse erythrocytes, we found two closely spaced glycoprotein bands in the 30 kD region that reacted with both FUB 1 and LPS-serum. One of the molecular weight markers, bovine carbonic anhydrase which is of a molecular weight of about 30 kD, electrophoresed in the same 30 kD region also reacted with these antibodies. Carbonic anhydrases from a range of mammalian species were found to be crossreactive with FUB 1 and LPS-serum by Western blotting, whereas human glycophorin A and human asialoglycophorin were not recognised by the antibodies. FUB 1 specifically recognises both native and denatured bovine carbonic anhydrase in ELISA assays. The serological identity of the determinants of CA and BrMRBC was confirmed by specific absorption of both FUB 1 and LPS-serum with BrMRBC and normal mouse erythrocytes. We propose that a native autoantigenic epitope on erythrocytes may be revealed by the proteolytic action of bromelain and that this determinant is associated, at least in part, with carbonic anhydrase.

Sequence of a novel carbonic anhydrase-related polypeptide and its exclusive presence in Purkinje cells

I isolated a mouse cDNA clone encoding a novel polypeptide which has strong homology with carbonic anhydrase. Unlike the other carbonic anhydrases, it has an additional N-terminal domain with a glutamic acid stretch and an arginine substitutes one of the three histidine residues which bind zinc ion. In the central nervous system, carbonic anhydrase is known to be expressed only in glia cells, but this gene is expressed in neuron, but only in Purkinje cells.

Light microscopic histochemistry of the postnatal development and localization of carbonic anhydrase activity in glial and neuronal cell types of the rat central nervous system

The postnatal expression of carbonic anhydrase (CA) activity in glia and neurons was investigated by a modified light microscopical method of Hansson. Strong CA activity was observed during the first postnatal week in ameboid microglia, clustering in the cingulum, the periaqueductal region, the roof of the lateral ventricles and the white matter of the cerebellum. The intensity of staining gradually decreased during the second week and finally disappeared. From the 9th postnatal day on, cerebellar Purkinje cells expressed strong CA activity, which completely disappeared by the end of the investigation period. CA staining of the oligodendrocytes and pericytes could be observed from the first postnatal day on. The present results raised the possibility that carbonic anhydrase activity may play a role in the regulation of the development and proliferation of some cell types, perhaps via intracellular pH changes.

Carbonic anhydrase III in the salivary glands and kidney of the Japanese monkey (Macaca fuscata)

Carbonic anhydrase III (CA-III) was found in muscles of the Japanese monkey by the double immunodiffusion test and western blotting using antiserum raised against equine CA-III. Immunocytochemical localization of CA-III in the salivary glands and kidney of the monkey was studied using an avidin-biotinylated glucose oxidase complex. CA-III was found mainly in the striated duct and interlobular duct cells of the parotid glands. In the submandibular glands, striated duct, interlobular duct, and excretory duct cells were strongly stained for CA-III. In the kidney of the monkey, CA-III was localized mainly in the dark cells of the collecting duct at the medulla and in the epithelial cells of thick limb of Henle's loop.

Histoenzymological light and electron microscopic localization of carbonic anhydrase in the rat superficial pineal gland

A histoenzymological method for demonstration of carbonic anhydrase (CA) was used for cryostat sections of superficial rat pineal gland. Light and electron microscopic analysis showed a high concentration of this enzyme in stellate cells, particularly heavily distributed under the organ capsule and scattered in the parenchyma, where they form a widespread three-dimensional network. Most of the pericapillary spaces were lined by CA-reactive cells. The reaction product, in the form of strongly electron-dark precipitates, was localized in the cytoplasmic matrix, whereas organelles, except for some mitochondrial intracristal spaces, were CA-negative. On the basis of localization and morphology of CA-positive cells, we conclude that these represent glial (interstitial) cells.

Analysis of parvalbumin and calbindin D28k-immunoreactive neurons in dorsal root ganglia of rat in relation to their cytochrome oxidase and carbonic anhydrase content

Histochemical and immunohistochemical techniques were used to determine relationships between the parvalbumin or calbindin D28k content and the cytochrome oxidase or carbonic anhydrase activity of neurons in lumbar dorsal root ganglia in rat. Subpopulations of dorsal root ganglion neurons that displayed parvalbumin- or calbindin D28k-immunoreactivity were classified as containing either light, moderate or dense histochemical reaction product for cytochrome oxidase and either a positive or negative reaction for carbonic anhydrase. It was found that approximately 90% of all parvalbumin and calbindin D28k-immunoreactive cells exhibited dense staining for cytochrome oxidase and that 87% of parvalbumin- and 76% of calbindin D28k-immunoreactive cells were positive for carbonic anhydrase. Conversely, 85% of all cells with a dense cytochrome oxidase reaction contained parvalbumin and calbindin D28k. Although not quantified, it appeared that many, but not all, carbonic anhydrase-positive cells contained parvalbumin or calbindin D28k. These results indicate the existence of a subpopulation of primary sensory neurons that contains parvalbumin and calbindin D28k and that expresses high levels of cytochrome oxidase and carbonic anhydrase activity. It is suggested that primary afferent neurons with this cytochemical profile transmit a sensory modality that requires them to discharge rapidly and/or frequently. The existence of a subpopulation of carbonic anhydrase-positive cells that lack immunoreactivity for parvalbumin or calbindin D28k suggests that the role of carbonic anhydrase in some sensory neurons is unrelated to functions requiring these calcium binding proteins.

Quantitative histochemical analysis of cytochrome oxidase in rat dorsal root ganglia and its co-localization with carbonic anhydrase

A quantitative histochemical method was developed and standardized and then used to characterize the heterogeneity of cytochrome oxidase activity among primary afferent neuronal cell bodies in dorsal root ganglia of rat. In addition, the relationship between cytochrome oxidase and carbonic anhydrase activities in these neurons was determine. In tests of the procedure, the density of cytochrome oxidase reaction product evaluated repeatedly in individual neurons within sections of ganglia was found to increase linearly over incubation periods of up to 6 h. The heterogeneity in cytochrome oxidase activity in ganglia was not simply a reflection of the heterogeneity in ganglion cell sizes. On the whole, each class of ganglion cell exhibited the full range of staining densities encountered but intense staining was observed in many more large type A cells than small type B cells. The latter, together with their termination fields within the substantia gelatinosa of the spinal cord, were lightly stained. A significant positive correlation was found between neuronal size and staining density (r = 0.43). However, the large scatter in the plot of these two variables suggests that the expression of cytochrome oxidase in sensory neurons is governed to a considerable extent by properties of these neurons that are unrelated to their size. Analysis of cytochrome oxidase and carbonic anhydrase activities in the same ganglion cells revealed that all neurons with dense staining for the oxidase were anhydrase positive. Conversely, however, some intensely anhydrase-positive cells exhibited only light staining for cytochrome oxidase. The heterogeneity of cytochrome oxidase activity among neurons in dorsal root ganglia may be related to the steady state electrophysiological activity of distinct populations of sensory neurons which in turn may be related to the specific sensory modalities these populations transmit. The observation that some neurons with the greatest abundance of carbonic anhydrase do not contain high or even moderate levels of cytochrome oxidase suggests some degree of dissociation between the functional requirement for carbonic anhydrase in sensory neurons and the rate of energy expenditure in these cells.

The immunohistolocalization of carbonic anhydrase III in the submandibular gland of rats and hamsters

Carbonic anhydrase III has been localized using the avidin-biotin-glucose oxidase complex (ABC) method in the submandibular gland of the rat and hamster. This isozyme, which is predominant in skeletal muscle, was observed in intercalated duct, striated duct and excretory duct cells in the rat submandibular glands. In contrast, only some striated duct cells in hamster submandibular glands were stained.

Differential effects of distal and proximal nerve lesions on carbonic anhydrase activity in rat primary sensory neurons, ventral and dorsal root axons

The effect of proximal and distal peripheral nerve injuries on the histochemistry of carbonic anhydrase (CA) in rat dorsal root ganglion (DRG) neurons, and myelinated (MyF) dorsal and ventral root fibers was studied. Sciatic neurectomy induced no change. Contrariwise, 7 days after lumbar spinal nerve section the numbers of CA-stained ventral root MyF and DRG cells at the L4 and L5 levels decreased to 73.2% and 51.9% of their original values respectively, although the numbers returned to normal by the 90th postoperative day. Dorsal root MyF followed a similar trend, albeit with some delay. Major morphological changes comprised atrophy of dorsal root sensory neurons and axons, particularly in long term experiments, as well as nuclear eccentricity in DRG neurons. These results suggest that, depending on the site of lesion, the rat peripheral nervous system (PNS) either maintains or quickly restores its capacity to synthesize CA. They stand in contrast to the long-lasting metabolic dysfunctions reported to occur when primary neurons are disconnected from the periphery. It is uncertain whether this difference is due to the critical role of CA in neuronal metabolism.

Carbonic anhydrase and horseradish peroxidase: double labelling of rat dorsal root ganglion neurons innervating motor and sensory peripheral nerves

Dorsal root ganglion neurons supplying peroneus longus, soleus and gastrocnemius medius muscles and the sural nerve of the rat were labelled with horseradish peroxidase and analysed for their carbonic anhydrase content. Staining of the sections was done either on the same or on alternate slides. Both methods led to the same results, despite a slight fading of the carbonic anhydrase reaction in double-stained sections. The data indicated that the muscles under study were supplied by approximately the same number of horseradish peroxidase-labelled cells, irrespective of their differences in size. 74.9% of these labelled neurons had diameters exceeding 30 microns and 52.4% of them also stained for carbonic anhydrase. The double-labelled cells represented 66.9% of the population of large neurons (greater than 30 microns) and comprised most of those measuring over 47.5 microns. Richness in carbonic anhydrase of the large muscle afferent neurons may be linked to their innervation of the stretch receptors, as components of an active apparatus which includes the gamma motor axons which also stain positively for carbonic anhydrase. In contrast, the ganglion cells supplying the sural nerve were almost totally devoid of carbonic anhydrase, as only 6.4% showed double labelling. This contingent possibly represents the muscle afferents of the small motoneural population which supplies, through this nerve, part of the foot musculature of the rat.